I don't know what I'd do, but re: utg+1's hand
I would be pretty surprised if he had a big pair
People seem to be terrified of the utg limp+raise, but like 90% (literally) of the time I see it it's a medium pair that limped for set value and now wants to get it headsup with the big pot forming. That said, I would still guess it's an overpair that's going all the way, but a set is also possible, which would decrease your equity more. Also, I tend to play more in the $10-$30 range, so maybe $100 mtts are different.