I’m sure a trickle of water gets in but its a pretty tight seal. If anywhere, it gets in where the straps go over my pecks. But, not on the back or sides at all.
I’ve done several sprint distance triathlons using only the bottoms and have posted some really good swim splits, even holding the fastest swim split overall in a race last fall. (only to be overtaken on the bike, but that’s another story.)
But, like you, I was a little bit skeptical, so I did a little unscientific test and did some 100 repeats in the pool. I also asked a buddy to do the same with his T1.
First with T1 top and bottom - held 1’08’’ avg for several 100 repeats. (short course yards)
2nd with T1 bottom only - held 1’09’’ avg for several 100 repeats.
3rd with no wetsuit - held 1’20’’ avg for several 100 repeats.
My buddy’s results yielded the same conclusions, just different times.
After about 2,000 yards of 100 repeats, I was getting tired. But, the results proved, to me at least, that wearing the T1 bottoms alone is faster than swimming without any wetsuit yet does not cause considerable disadvantage of using both pieces.
At Ralph’s half IM, I wore the top and bottom because it was freaking cold. But, in most races in the Southeast, the water is not that cold, so I just use the bottoms. That’s why when people always say they don’t want to spend that much on a wetsuit, I always recommend just getting the T1 bottom. They can always purchase the top later.
Next week’s Gulf Coast half IM is expected to be a wetsuit swim while the air temperatures will be very warm. I also don’t ever overheat by just wearing the T1 bottoms.
BTW, I have nothing to do with Desoto. I don’t even know if Desoto would appreciate me telling people to only buy half their wetsuit. I just know what has worked for me. Good luck.