I like variations in my units, e.g. I don't like to use for a marching unit one single pose of one set and then have 120 in my unit - all clones.
Instead I like to mike the same poses of different manufactueres so 6 different marching men from 6 different manufactueres look that much better, then add some head swaps and it even looks better.
The now dead range of Woodenfelds had about 40 different soliers - in just one pose of Right Shoulder shift, war a joy to paint up a unit like this and have 40 individual characters.
I only mentioned ACW because Strelets said they would be doing some as I remember. Personally I am not a big fan of ACW for the reasons you mention, but I am happy for them to be done so long as other things are done also.
You can use Italeri Napoleonic French Horse Artillery for RHA with some conversion, except that the wheels of the guns have to be replaced by bigger ones, for example from the Revell Napoleonic British Foot Artillery.