I am currently about the same weight as yourself. I went the MTB route for strength as I thought the thin 700c wheels probably wouldnt be able to take it.
I too find my hands and fingers get numb and my palms often ache. I went the hardtail route but that said...my off road part of my commute is a few miles on the canal towpath which is hardpacked and some parts tarmaced. (total commute 8 miles each way) I have been considering swapping the sus forks for some rigids.
I do agree that although MTB tyres roll nowhere near as well they do offer a bit more comfort.