I have moved from the 452 to the 4620 with only a few minor problems. (after a week of misery)

1.comment out config settings in the .inc file and remap the memory in the .bas file for picbasic pro.

2. make a small change to the portA settings in my code, as the 4620 has a different width.

Other than that it works well, as far as I can tell. I2C worked without any mods, not using PWM so don't know about that. Code's up to 37k now, 20Mhz,32bit math, multiple menus, LCD, HSER, Membrane keypads, interupts etc...

Chips from Digikey, $1 more than the 452 for an extra 32k code space, not a difficult decision.

need any help, let me know