At first I hung the hammock too slack, and I couldn't find a comfortable position to sleep in. Either my feet were way up high (sleeping down the middle) or my feet slid off the hammock (trying to sleep at a diagonal. I recognized my mistake and got up and hung the hammock tauter -- but perhaps not taut enough. The second time I could get a decent sleeping position. The Gossamer Gear pads are better than most in "sticking" to the hammock fabric and actually don't slide around too much. However, the temperature soon dipped to -3 C (27 F), and I could feel a chill on my back and sides of arms. After a while contemplating what would happen next, I got up again to move one of my thin pads (I'm using three, of different shapes and sizes) to my torso region). That helped a little bit, but it didn't seem like enough. I fell asleep anyway, though, and woke up a bit chilled at 2 am. Had to get out to pee, and my back was cold. Out of the hammock a third time. Ate a few nut bars, but the water in the nozzle of my bladder had frozen, and I could drink. Got back in hammock, but did not fall asleep, or just dozed off, reluctant to do anything about the cold. Near 4 am, I mustered the resolve to do something about the cold, realizing I would otherwise not sleep anymore tonight. The temperature was now -4 C (25 F). Time to look for a spot on the ground. After 5 minutes of wandering around, cold, I found a decent spot right behind the tree my hammock was tied to. I got the sleeping pads and quilt out and settled into a decent sleeping pose a few minutes later. This time my pads were sufficient for the leaf-covered ground, and I was not cold after that.
I woke up, not exactly refreshed, at 7:30 am. Packing up at -5 C is not always fun. I quickly opened the velcro-secured hole in the center of the quilt ("Jacks R Better Rocky Mt. No Sniveller") to convert it to a coat, or "serape," and put it on immediately. It did help keep me warmer, but cold advanced up my body from my legs. Luckily, my hammock setup requires no knots, and several minutes later I had packed up and set off on my bike, my teeth chattering.
My sleeping pads are sufficient for temps roughly above freezing in the hammock. If it looks like it will be colder, I'll switch to a ground setup, where I should be able to manage fine to about -7 C (19 F). If It gets colder than that, I may get cold. Moving from the hammock to the ground during the night is no fun (especially if it's raining!) and should be avoided at all cost.
I expect many nights near freezing on the PCT in April to early June and maybe a couple nights as cold as -5 to -10 C in Southern California (you never know). The nights I have to sleep on the ground, I will not need to set up a bug shelter, because at those temperatures the bugs are not active anyway.