We don't really know what they are doing with the GUI. I would suspect that it will not look quite the same as the 950/970/990 menu structure simply because of how much has been added, but they may try to retain as much "keep it simple" as possible.

As for SACD/DVD-A decoding via HDMI, any HDMI input that will take multichannel PCM will do DVD-A (once MLP is unpacked by the player, that's what you end up with). I don't recall if Sherwood has mentioned DSD support for those (few) players that can output it, but I would say odds are better than 50/50 they have DSD support. (Of course, opinions on whether it sounds better to output DSD or PCM from SACD's vary from person to person and seem to depend heavily on the equipment being used).

As for beta testing, you can always just ask them - that's how I ended up doing testing for OPPO's 981HD two years ago. At one time Oytlaw had a beta test application of some sort, but I don't know what they do now.