I used to play with huge units but not so any more.. It was fun to get more men on the battle field, but the unit sizes where just getting hard to move about... 120 Archers in 2 rowa.... Get few units like that on the field and things get pretty crowded... Also, there is not that much different to Default, as the units are twice as big, cost twice as much and take twice as long to build... You essentially end up with the same size army, just in bigger lumps... (the fact that retraining on huge still only took a single round added a little strategic difference..)..

So no, I don't see much economic difference in the two modes... I couldn't really tell if it made much difference to the AI, but it did seem slow down the start of the campaign a bit...