I don't understand this kerfuffle about the 50 hp breakpoint Bullitt mentioned. Yes, he technically should have slipped the word "over" into the sentence that said at 50hp it's best to go with a utility size frame but is anyone really having trouble understanding his intent?? For starters, there really are no utility size tractors built these days that are less than about 60 hp. More importantly, his main point about CUTs over 40-50 hp being simply identical to the lower hp versions except for engine tuning is the critical (and correct) point.
Unless you have only PTO power concerns, it makes sense to ignore the overpriced 50-60hp CUT category and choose between a 40-50hp CUT (IMO 45 is top unless the 50 has stronger loader) or a utility tractor virtually all of which these days have 60 or more HP.