I've been using the DS Logic for a while and found it great, though I've just lent mine to a friend since he's interested in buying some.
Software has changed since the serial trigger plots above were done (I'm not sure if serial trigger interface has changed though), I've used the advanced serial triggers to capture some rare awkward to find events, the serial decoders used for triggering are built into the FPGA. (Verilog on github along with reprogramming instructions)
The key features I liked / use:
* 16 channels I use this most of the time (100Mhz will normally suffice)
* 400Mhz (I look at some signals where 100Mhz isn't quite fast enough, the 4 channel limit is little low, but constrained by DRAM bandiwdth)
* 16M sample buffer, making easy to see what else was going on during a long wake interval <-- this great
* "Complex" Hardware triggering (yes it is built into the FPGA) with several trigger states
* streaming @ data rate below ~10MB/s
Features I've not used:
* trigger in
* trigger out
* clock (because my system doesn't have a visible clock synchronous with the data)
Minor gripes:
* The complex hardware triggers only work up to 50MHz, so I've not been able to use them on the 80Mhz QSPI bus I monitor
* The LA signal cables are a little fiddly to attach, even compared to a cheap Rigol.
* Software should make it easier to display buses and bus states, I use the "parallel" decoder but the last transition is not shown, and it only decode to a number.
Overall (bar the minor gripe above) I've been happy with the Sigrok derived software, though more features would be nice (I've got used to segmented memory on regular scopes and figure an FPGA based one could manage something similar).
Triggering, even advanced triggering was easy to setup. Measurements are easy to make, with cursors.
Overall it's got the speed many of the cheaper ones are missing and a great buffer depth, Verilog available to add trigger option if needed.
At $99 I've found it great purchase.