NEXUS won't completely replace APEX yet for me in online multiplayer games as I'm far more experienced with m/kb, but I can at least compete with controller users with a NEXUS. I've dropped APEX for all single-player gaming as NEXUS is so much easier to setup on the desk or couch and is an absolute blast to use 
I'm probably in the same boat here. I think this is great for controller users, but I'm not one of those, nor will I ever be. I hate sitting with my hands in close proximity like that on a controller in general as it's super uncomfortable. Thus I will remain M&K. Which is somewhat disappointing as this is probably the first XIM product I won't buy.
With that said, I thought one of the main selling points of the XIM (and often used as an argument in the "is it a cheat device") was that it is really for people who want to use "any" input method of their choice, which is quite necessary for disabled folk, which means this device won't be for them, at all. Of course this won't be an issue as long as APEX continues to be in production and support.
With that said, it's great to see a motion controller that will probably never be topped, so good job OBsIV. It's definitely a needed device in general. I would def use it if I used a controller. The only time I use a controller right now is when I'm using Xbox streaming on my phone (rare), which I doubt this device will work with.
Anyway, I just hope it does not stifle continued improvements on the XIM APEX, specifically on the software front, as I believe there is still room for improvement there. A lot of features/requests that have been made over time that have gone to the wayside for more important things.