I would really really like to be able to have much larger tactical battles... Also i hate the army limit idea. Maybe make it so that large armies get some penalties without the right technology but we should still be able to throw a massive rabble at the enemy.

+1 for large armies & larger battles.  No, make that +2.

I'm not sure this is the best solution, and it may have balance implications as well (spawning 20 groups of archers, for instance).

I honestly don't really care what they do with troop sizes, as long as they balance them out with other available options. That said spearmen start the game with 18 attack already (24 if strong). Their damage output is pretty solid, and actually rather scary if they get the first attack. Increasing these numbers will cause their damage to scale well beyond intended, even when you take armor into consideration.

The problem appears to be their hp. They start with 18 and can inflict up to 24... that seems a little off. Doubling their hitpoints seems like a better start than increasing all of their stats via unit size.

As Sythion mentioned making armies bigger could have additional implications with various unit combinations (most probably ranged). It's something that I wouldn't mind testing, but I'd much prefer they first focus on making tactical battles interesting.

Of course there are going to be balance implications if you double or triple the number of units in tactical battle. But there are numerous balance issues already.  Starting with the balance issue I think this addresses: that heroes are OP and that the optimum stack is all heroes and no mundane units.  In fact, this balance issue is so great that it's hard for us to test any other balance issues (for example, archers are too effective against decently armored units).

And yes, you can get something like the same effect by just upping the base HP of mundane units.  But making mundane units as powerful as heroes is just a terrible idea.

Do you remember the first visuals of WoM ? There were plenty of men.

It's not an elegant solution though, and doesn't fully address the issue.

1. Units can still die, champions still cannot. This means more resources are needed to compete vs champions, especially since there will need to be many more units to compete with champions to make this viable.
2. AOE spells, which are already broken, will still dominate large groups, and invincible defenders are invincible regardless of how many troops attack it.

I'm going to bring up my preposition again: Make it so that champions can only defend against 1 or 2 units in a stack, and only attack 1 or 2 units in a stack. By default, champions aren't meant to be soldiers single handedly fighting off entire armies, though it's certainly wise to add abilities that can be picked up that allow them to perform better in combat against stacks.

You're also missing the point. My idea is not to make heroes suck. My idea is to make armies work well against heroes, and to make heroes require investment in war-like combat to be a huge boon in wars. (they will still be great at adventuring, which is what the archetypical hero is usually viewed as.)

Numbers are just numbers, and should be used in whatever way they work best. My way works better because of the points I brought up: If you simpply allow more troops in combat, heroes will still be OP vs large armies, and large armies will be too resource intensive to be a viable strategy. In the end, you'd have to nerf heroes anyway to make your plan work.

I see, you're thinking rock-paper-scissors, kinda like the RTS Age of Mythology.  The problem with a rock-paper-scissors approach is that it makes all the units basically equivalent.  Which is good for balance, but I really don't think that is a good mechanism for a game like FE.  The champions are supposed to be awesome, I personally think they are the heart and soul of the game.

Two points I want to raise about this response.

1. Not RPS at all. I hate RPS, it's a very simple game, and does not really enhance strategy. First off there's only two types in consideration here, so RPS isn't really possible when we're talking about units vs. champions. What I'm saying is simple. By default champions do not get to utilize their full potential against units. This is to balance them against units, which everyone (yourself included) agrees needs to happen. However, a champion can conciously be made into a war powerhouse by taking the appropriate traits. Doing so would hamper his/her ability to take advantage of quests and clear monsters from the board (because he's not taking traits that benefit combat except vs. groups), actions which champions are very good at and fits with the "theme" of champions.
2. While champions are "supposed to be awesome" is a point I agree with, I don't think they are supposed to be so awesome there's no point in even building units. That's how they currently are, and would remain even with a troop limit increase.

I would love to see additional soldiers shoved into one unit, but I'm reticient about having more "units" in a battle.  Remember that you have to take a turn for EACH individual unit on the battlefield.

If you have like 20 units per side, that's FORTY moves per turn.  This can really slow a tactical battle down to the point where it becomes a chore.

I think there has to be a happy medium between having enough units so that it seems "epic" and not having so many so that it seems "epically slow."

Are we even sure the game can display units bigger than the current maximum, without a serious art revision?

In chess the queen is the most powerful, but she's not all powerful.  The pawns are the weakest, but they are often pivotal in determining victory or loss.

How many units are on a chessboard?  How many in Stratego?  Games are not a chore because they have too many pieces, they're a chore because they aren't interesting.  Adding units doesn't magically make any game better or worse.  In my opinion, adding pieces to FE's tactical battle would make it more interesting.  I think the major difference between FE's tense and challenging early game and it's less compelling late game is that battles do not scale at all.

I don't understand, armies of mundane units killing monsters already happens in FE as it is.  If you want to send your 20 unit mundane army to face a dragon, sure, you might manage to kill the dragon, but you'll lose most of your army in the process.  Congratulations, you just spent ~100 seasons worth of production.  In the meantime, the neighboring territory is marching on your undefended cities.

Honestly, I don't see the problem.