I've had exactly your experience. I really, really wanted my HH Asym to work, everything seemed so brilliant and it solved so many issues, but I just couldn't get comfortable in it. Aside from the same issues you have had, I just couldn't get comfortable with the way the hammock sides pushed on my arms and shoulders; it felt like I was being smashed, and I couldn't just lay my arms out to the side a bit.
Also, after a time, I had a strange difficulty in breathing, as if the hammock wrapping around me was suffocating me, preventing my lungs from fully inflating. This might be in part due to the sides pushing in on me. I just felt a bit claustrophobic with all the squeezing going on.
I tried sleeping with an undercover, a foam pad, a Thermarest Prolite 3, and a Big Agnes Insulated Air Core pad. While each had their strenghts and weaknesses, I could not find a 'sweet spot.'
The final deciding factor for me was, after a few frustrating hours of tossing and turning, I finally lay my Big Agnes pad out on my concrete patio. I felt I could finally breathe again, let my arms stretch out to the side, flip to my stomach; I knew immediately the BA on the ground was the better choice for me.
Lastly, I took a long, hard look at my backpacking habits, and decided that I mostly prefer to sleep at or above timberline when I can. While a hammock on the ground is acceptable for this, I felt that my GoLite Hex 3 shelter was more appopriate for high winds and mobility in drawn-out storms.
I haven't completely given up on hammocks yet, though. my dirty little secret is that I am 6'2", 210lbs, and my Asym was only rated to 6'0". I would like to assume a longer hammock would solve alot of my comfort problems, but I haven't gotten around to purchasing a large one, and I'm not looking forward to adding the extra weight. I am also interested in Ron Moak's new design, but with an 8 week shipping date, I don't see that happening anytime soon.
For now, I am consigned to dealing with the mud, and spending more time looking for level campsites.