That's amazing and i hope you will keep working on it, phh. You probably noticed that the XD development is gone, and since GPD had the terrible idea of releasing a new XD with a new soc this will probably be the only chance for the original XD users for having a new Android version. Also thanks PsyOps for the help you're giving to him.
Well, it's not that GPD had that idea. they are forced to do it, because RK3288 will be out of stock. So current XD was going to end manufacturing anyway. New model will be called XDS and will use an hexa core MTK, the same that comes with xiaomi mi pad 3. They have a proto ready to test.
I am not defending GPD though, I understand your point they could release a new android version for RK3288, although they had issues to get a perfect stable firmware as far as they told me, so I suppose they resigned for that reason. They never gave me a recent SDK yo try to port it by myself, so I am late to the party.
No idea what mali libs use this 7.1 release, I hope they are different from the ones used in LP or android M, because Saturn emulation works bad with them. But maybe the SDK phh has in his possesion has new ones provided by RK.
I am not confident with new XD model anyway, unless is too cheap the GPD WIN is a much better device in all means, and even if it's more expensive, it costs every penny,