You should update the firmware before doing anything else to it. A few features will be locked and some will behave different, like the brakes for example. Mine still works fine. I haven't felt the need to add more caps, as the ESC doesn't get hot at all.
The limit is 3000kv. I tried a two pole 3600kv motor and it just cogs. I tried a 3100kv 2 pole more and it was a hit or miss. Still works well with a 2700kv 4 pole motor. I haven't tried the 4800kv 4 pole motor yet, to see if it works or not.
Here's a vid of the ESC running on 6s A123 and a 2700kv motor.