both are significantly warmer than any other boss delay out there so if you have one or the other i wouldn't worry about it.
i can say that i don't think the DM-2 is worth $75 more than the DM-3 (which is about the price difference on their ebay clearing prices). if i hadn't picked up my DM-2 under-valued in a trade, i doubt i would have gotten it.
I am not savvy when it comes to pedals... could you swap a 3205 chip with a 3005?? or would it melt? I know the pedals have different components to change voltage at acertain part... so is it not possible even with a socketed chip?