Don’t know why you would destroy the microprocessor, as long as you double check your connections before applying power.
On that note wether or not you are using an replaceable microprocessor, if you pump 350v DC though any arduino board you are going to destroy a lot more then the microprocessor. The seeeduino is nice because it’s cheap and also very discrete, and with the SMD version of the atmega you also get 2 extra analog inputs over the standard DIP version, they come in very handy, a lot of people seem to look that over.