Crotchless for comfort, nappy for, ah, survival of the species?
I suggest you try to borrow some harnesses form fellow sailor before you make final decision. If you plan to spend a lot of time in the harness take a serious full at a full that has the lumbar support. You can move it around till you find the right spot. I really like mine and have no sore back anymore that I use to get with the old diaper type from the old days. Have the straps on the legs really takes the pain off the crotch.
Looks like we're leaning toward the Hobie Convertible. I tried one on this weekend and it was very comfortable.
this may be worthy of a new post but i figured since we are on the topic of trapping... what exactly is the proper technique for hull flying? do you lock the mainsheet or just hold it by hand so you can make small adjustments to everything? and how much should i be able to lean back while trapped out?
I'd leave it uncleated in case you get a puff and start to go over.
Leaning angle depends on how much you're trying to counteract the heeling angle of the boat.
It may be best to get acclimated to the hull flying first and the different ways you can use to keep it flying, ie. mainsheet, steering, hiking out.
and how much should i be able to lean back while trapped out?
Practice this technique while on shore (with helper holding down the boat)and then incorporate with your hull flying. You'll want to be "higher" in the trapeze at first, so you can see everything on the boat and get in and out easier. As you gain experience you may adjust your trapeze lower to gain more leverage.
thanks guys, i guess i need to lengthen the dogbones a little, when i am flyin high, im about vertical on the boat
Adjust to what's comfortable for you. Optimally, the crew should be perpendicular to the boat with the skipper a little above so he/she can see over the crew.
Guys:
I just cleat my main and play the tiller. When hull gets to high head up. To low fall off. Start with angle a little higher till you get use to it. Just takes practice. I won a hull flying contest once. You will get the feel of it with time. It is a lot of fun.
Doug Snell
Hobie 17
www.tcdyc.com
Unless you have biceps and traps like Lou Ferrigno, you're going to have to cleat, and play the tiller, as Doug said... of course to a lesser extent you can use your legs to increase/decrease the extent of your hiking.
In a serious puff you can quickly snap the mainsheet out of the cleat and sheet-out to save yourself. "Don't worry about me, save yourself..." LOL...
Yep, there's somethin' fine about flying a hull uninterrupted for 2 or 3 miles... 
well, now that you mention it... i do have some fairly strong arms from the climbing i do.... there have been times when i wasnt really able to uncleat the main in time and i went over, so ill have experiment around a bit, thanks.
OH and a word of advise. Warp the mainsheet around your hand. I once was on the wire flying a hulls and the trap rope broke. I was trolling int he water and having it wrapped kept me with the boat. Not fun to have to swim to a boat drifting faster than you can swim. You will have a great time once you get the hand of it.
Doug