i have the same kit
450Xl with 3550kv motor and 25A esc on TP 2100 3 cell

i have about 6 flights with it so far and the esc is running about 109*F. from what ive asked and seen on the forums it should be ok as long as you dont 3D with it just basic flying. i have the motor throttle curve set at 90 mid stick and 100% after i guess the motor runs better at full throttle. also the pitch on mine is 0 at low stick it hovers at 5* mid stick and max at 9*

the biggest thing is to be sure the gear mesh is good and the tail belt is not to tight these are the things that makes the motor/ESC hot. also that you dont run lots of pitch at low throttle

i asked basic same Q here
http://trextuning.com/phpBB2/viewtopic.php?t=5228