I owned two Feeldoes; the slim and the stout.
I found that they both worked fine for f/f play, but the slim is a little floppy. The stout is a bit sturdier, but the extra weight kind of pulls it down when you wear it. Definitely a kegel workout!
For f/m play, the extra length on the slim made it easier to wear with a harness, but it wasn't as firm as I wanted. Without a harness, it's really difficult to use for anal play.
I think the Share will be my choice in the future; The Feeldoe was fun, but the Share looks like a better design, overall.