I haven't experienced any overheating, but I have seen some annoyingly bizarre battery draining issues which appear to be related to the phone keeping HSPA data connections active. I think I've finally resolved this issue, by doing a full reset. Prior to going down that path, I could resolve the issue temporarily by taking out the battery and SIM card for 5 minutes. Might be worth a try.
I recall reading somewhere that a number of odd battery issues were resolved with post v110 firmware. Hopefully Telecom will approve the updated Firmware sometime this century.