I have had a Lemon-RX (previously known as Orange-RX) DSM2 6-Channel Receiver (PPM + UART)
sitting around for a bit, and finally got around to hooking it up to my logic analyzer and checking it out today. I was interested in this RX as an inexpensive option if you need PPM output and run Spektrum/JR gear. I knew from the spec sheet that the channel resolution on the UART output was a bit coarse. It runs DEC(66) ~ DEC(134) full scale, giving only 68 disrete levels. The PPM output is a bit better with a minimum change of about 12 microseconds, so about 83 steps. Bumping my TX endpoints up got it up to 100 steps. So that is not great, but OK for drone use IMO. The stability and jitter looked really quite good at around 1 microsecond.
This RX comes as a bare board with a 3x7 header and 3x2 header soldered on. It is a bit longer than an AR6200 and a bit narrower. Some careful work with a soldering iron should allow for removal of the headers and soldering in a 3 wire pigtail if all you need is PPM, leaving you with a very thin package.
I have not done any range testing, but my expectation is that it should be similar to a real AR6200 as they are using the Cypress RF chipset. Seems like a pretty good PPM option for only US$ 15.30 (plus shipping of course).