I've done quite a few HIMs and one IM. I'm currently training for my second IM. I wear a 2 piece suit because I like to be able to stop and pee without fussing with a 1 piece. I'm not at a competetive level where I'm prepared to pee in my shorts like the pros.

Tri shorts do have a minimal chamios, but it's not hard to get used to and I've been comfortable at both the HIM and IM distances riding this way. You just have to encorporate it in your training schedule, use the tri shorts for your long rides.

If I was doing more Oly distance races, I'd probably buy a 1 piece too. They are comfortable, not weird at all under a wetsuit and look great!