I have had no issues with Daiichi 1730 sizes 14 to 10 straightening out. Fishing boatmen and leeches, hard hits, fish 5 to 15 pounds
That said I really do like the Mustad C49s from size 14 on up.
As to needing it to float, there are several issues there. At times fish are not taking near surface and a bit of float ability is good so I use the Jennings Ultimate Boatmen type body or just create one out of foam, then use it on a NON-Density compensating full sinking line so when I cast and let the line sink, there is a belly that will have formed in the center area. I then strip the fly in and in doing so, it first drops close to the bottom then rises as the line is pulled toward the boat.
I also use weighted versions (tiny bit of flat lead at the bottom of the shank near the eye) in shallow water and let the boatman sink then strip it in with pauses.
Certainly if fish are taking them on the surface that is the fun way to fish but all too often one finds fish full to nearly bursting with boatmen and backswimmers yet there is no surface action. It is times like this when one must do some thinking about how to entice strikes...