am I the only one who thinks this is a marginal shove? What is his likely range?

has already been discussed, 8's thru aces? aj-ak, and maybe KQ. if we knew he was calling with all of them, we have equity, but a few things to note.

a's thru jacks are more likely to begin with since some players might even fold 8s or nines utg to begin with, but further, he may call with only jacks thru aces, and aq, ak. so you have equity if he calls with his eights and nines, but slight negative equity if he does not. this may sound like he has to play perfect, but I suspect many people in utgs position have a cutoff of jacks or better to call Hero's all in (along with ak, and maybe aq). you hate to spend almost 10% on a flat call, but does anybody do that?

one other thing to consider. even if you have 5-10% equity, does a good player settle for that? I think they have greater inherent equity, and the M dictates there is still some game left.