this sounds cool, but keep in mind as you research the adventure tech, more powerful champions become available.
True, but that doesn't preclude champions leveling up skills. People like to form a bond with their 'heroes' and watching them level up enhances said bond, compared to just hiring a 'new improved model'.
i personally don't need to, and would rather not upgrade heroes manually. i would prefer if they at every few levels gained a random ability.
Not wanting to take the time to level champions is understandable, but some would enjoy it. As for the skill gained being random we'll have to agree to disagree (tho I notice your most recent post supports IWarMonger's proposal which isn't random).
I'm not sure what you mean by "uo" style rising...
Basically it's what you're proposing -- use a skill and it eventually raises. In UO (Ultima Online) if you hide your hiding skill goes up, mine then your mining skill goes up, etc. There's also a secondary effect -- your associated stat also raises. Table of Primary and Secondary Stats
shows the list of skills and their primary and secondary stat. So, if you hide your dex (primary) and int (secondary) stats will raise, if you're mining your str (primary) and dex (secondary) will raise, etc.
I mention the stats raising because as long as you're proposing the skills raise by use -- in for a nickel, in for a dollar -- may as well include the stats automatically raising too.
Your proposal requires keeping track of what skill is being used and/or enacting some method to choose what skill to use. Fighting to raise fighting skills is obvious, but how to 'use' farming skill would require a way to assign a farming task.
Perhaps buildings and/or techs could have a 'slot' to assign a champion to -- build a farm and assign Joe the Farmer to the farm's slot, build a market and assign Joe the Merchant to the market's slot, research caravans and assign Joe the Peddler to the caravan tech's slot, etc.
Automatic stat increase would be easy, just define a skill as having a primary stat (say str for fighting skill and lumberjacking, etc.), and maybe secondary/tertiary skill too if a more diversified spread of stat gain is desired.