My N=1 experience with Zipp hookless so far has been good. Can get tires on and off without levers which has very rarely been the case with tubed or at least not with Conti GP 4000 or 5000. Had one puncture that hasn’t sealed so far, and just stuck a tube in there. So seems best case is reduced chance of punctures as some will hopefully seal and you’ve eliminated pinch punctures. Worst case is putting in a tube which is no worse than it would be with a tubed tire apart from the sealant mess. Even the sealant mess isn’t as bad as I thought it would be - gives a good photo opp to any friends you’re riding with, but it dries out and peels off easily enough.
Not sure lack of tire choice is really much of an issue. There’s enough to choose from, and the ones I’ve tried so far (Pirelli and Schwalbe) seem decent. If hookless sticks around then would expect choice to increase. Guess the issue will be if wheel manufacturers decide hookless isn’t the way forward and adopt a different standard instead, in which case tire manufacturers would follow suit and at some point you’re left with wheels you can’t buy tires for with no resale value. Hopefully with ETRTO standard updated to include hookless and manufacturers as big as Zipp (=SRAM), Cadex (=Giant) and Enve apparently betting on hookless it’s here to stay. From what I recall, Conti were one of the last big tire makers to release tubeless tires, so maybe not a surprise that they haven’t released hookless compatible tires yet.