Have used cubietruck, seems to struggle with swapping, badly.
Hmm... haven't had any such problem.
As you say, mainline support is not good and is obviously part of the swapping issue I experienced.
I've had some trouble with the gigabit ethernet (solved by forcing it back to 100Mb/s), but other than that what's supported worked well. The "not great" was more about the lack of support of various elements (e.g. nand flash, OTG, audio, video, wifi) rather than the quality of that which is supported.
Stefan