Yeah the only issue with the faster spawn rate is performance *if* anyone has a lower end pc, otherwise it is okay. Since grunts don't give *that* much money we haven't noticed much issues with AoE abilities being OP, particularly because grunts are on hard as well.
Doggie: A bit of it comes down to preference, but after playing on hard you will realize how weak towers on normal are. The fact is a DG can stand in between multiple towers barely getting hurt - on hard it makes them more realistic.
Once you get past a certain level you can cap a flag near the enemy base defended by 2 towers, without destroying the towers - this is just plain wrong. Even when you upgrade towers on normal strength they become weaker and weaker as the game progresses.
The flag capture time is a pretty big one for us though, the normal cap times are insanely quick - you could cap a flag then be fighting a demigod off near it, and he moves a bit closer to the flag for 5 seconds and you lose the flag. If they changed the mechanics a bit it might not be as bad, but currently this can be really annoying.