Backpacker has it right, particularly with respect to the roll, botching that is what's going to put you at extreme risk. Though the required limitations for Utility category do accommodate the basic aerobatic maneuvers when properly executed, some aircraft build up speed faster than others when you point them down.
The problem comes when you treat a "normal" category like a utility. Some of those types build up speed very quickly, and a Tomahawk for sure, when they are pointed down. The roll is extra dangerous this way, because unlike a loop, you are inverted at a much higher speed already, and you're accelerating from there.
A part of the certification is the test pilot's assessment of the margin available for recovery from an upset before you exceed a limitation. The following photo shows the "G" I pulled while recovering test spins in a Cessna Grand Caravan, at gross weight, forward C of G. (Aft C of G spins were
very different!). Though the 3.8 G limit for the aircraft was not reached, (I only took it to 2.8 G during the recovery), that 2.8 G was reached at just about Vne, so there was very little left to play with before something was exceeded, and very little time to get it right. Without a G meter, that maneuver would have been extremely dangerous, as most pilots cannot sense G accurately, and blasting right past Vne while trying to not overstress would be the certain outcome. That is why the Caravan, like nearly all normal category aircraft is not spin approved. Not 'cause it won't recover form them, but because there is little margin for error.
This is the reason to not fool around with experimental aerobatics.
