I was the rebel in the group wearing a wetsuit (stylin' vintage 70's) on the Middle Fork a couple years back. Mid June, big water, snow on the put-in road.
I felt like I was the one dressed right for the conditions each day. On the calmer days 2 & 3 a hydroskin shirt was the right choice. Having the ability to layer down was nice.
Bring enough neoprene and you will be warmer than the dry suiters. Be ready to layer it up.
June water seemed to get us to camps (8 day trip) in about 2 hours. If your swimwear isn't comfortable, at least you won't be in it long. Enjoy that run. Lot's o' action - in 100 miles I was only able to drink 3 beers at the oars.