If I were to guess, and I am, the new Odyssey model is a refresh in an attempt to address the fitment issues with quite a few users, myself included. I was able to address these with some extra straps and slight modification, but some aren't as handy or willing to go to those lengths for something which should be comfortable out-of-the-box. The on-board bluetooth sounds like a nice addition as well. Not sure what the SDE reduction part is about, but if it ends up being a filter which reduces the image sharpness, I think I'd rather deal with the sub-pixels. There's a bit of silly speculation about native SteamVR compatibility (i.e. lighthouse tracking) but I seriously doubt that this will be the case. It'll be interesting, nonetheless.
On a side note, I put mine on the other night after not using it for a while, and I was absolutely stunned at how fast the controllers are picked back up by the tracking, once it is lost outside the view of the cameras (which is larger than the viewport FOV.) It's literally a seamless re-acquisition now. I.e. I'm not able to see the controller anywhere it should not be now. MS has been doing some great work in the tuning of the Mixed Reality platform since launch, and seems not to show signs of slowing. The PSVR2 had better have some tricks up it's sleeve, if it's going to compete with WMR once it hits the MS consoles.