I have driven both boats and would go with the ZR.
The Donzi handles and turns great and I thought it was more stable. It had t 575's, staggered. It is also better for passengers. I ridden in a Gladiator in rough in the back and was almost tossed out, there is nothing to hold on too or foot rest to brace with. Both are nice boats, but the Donzi has great lines and with the quarter canopies it makes for a nice quiet ride. I raced one in Miami and did not even have to pull face mask down on helment because of the canopies. The best thing to do is try both out and see which one!