You should look into the Roubaix line from Specialized. I own the Elite and have nothing but great things to say about it.
Like you I went from MTB to hybrid, lost weight and am now riding a road bike (and a fixie) without the pain. I am now 6Ft4 and 220.
I can really tell that the Roubaix is doing a fine job at smoothing up the ride; when I ride the track bike, I feel everything going up my spine, but on the roubaix... not a thing.
Good luck and welcome.
O.