First, as others have said, this .9 patch was a step in the right direction.  I like that there is a minimum 3 turns to create a unit; this stops unit spam and makes buildings a worthwhile choice.

That said, there's a big bug/exploit to turn production into gildar.

1) The easiest way is as Quendar/Magnar, design a slave unit with as low of a production value as you can (1 works well for this example).

2) Go to a city with a sizeable production capacity.

3) Add that cheap unit to the production queue.

4) Wait one turn.

5) Go to the city and click on Rush.  You will get gildar.

The problem lies in the two competing rules.  A) All units are minimum 3 turns and Rush costs are straight production required for unijt - accumulated production = gildar cost.  So when a player puts in a turn or two of substantial production and the production required for a unit is low, then gildar costs are negative.

Simple solution: make sure that gildar costs are always at least 1 (with rushing and throughout the system).

Long term solution: figure out a better way to handle 3 turn minimum, if that is a feature that will always exist.  Right now it leads to a lot of min/maxing (even ignoring the above bug/exploit).  For instance, if I need to occupy my city with 50 production per turn, and my slave unit costs 30, then I'm wasting 20 production x 3 turns.  It's not as big of a deal with non-Quendar races, so maybe just re-think slave costs.