OK... I just emailed Paul Galagher... the xshifter guy... let's see what he says?
This is speculation, but with all of the Kickstarter drama around the Xshifter project, they probably aren't selling them anymore. I think the production rights were sold to CELL and then they developed the new NXS shifter to replace it. I think it's a smart marketing move to leverage the Xshifter engineering and technology but ditch baggage attached to the name.
As with anything, caveat emptor. There are many cases where sound technology is corrupted by bad business practices. I took a chance on the Xshifter because I was able to get it at a discount through a liquidator. I knew I didn't have the customer support by going that route, but for the price I paid, it wasn't an issue.
I've been using it for almost 4 years now. The shifter servo is excellent. It has been pulling cable accurately and actually makes lower quality mechs perform better because you can fine tune the cable pull to a tenth of a millimeter for each shift. It also saved my butt in France when I had to replace my 9 speed cassette with a 10 speed one due to parts availability. Having that shifter made it a simple swap. I just reprogrammed it and instant 10 speed.
The mini wireless shift remote is just OK. It works fine, but the build quality could be much better. Changing the battery is a PITA with 2 tiny screws that hold the circuit board down to the case and the battery is underneath. The battery lasts a long time, almost a year, but if you ever have to change it on the road (I have) it's a pain. Also the rubber cover has to be in right place or water can get in. I learned this the hard way and lost a shift remote to corrosion. Luckily, I bought a few extra remotes with the unit. I now spray the circuit board with CorrosionX at the start of every season to waterproof it just in case.
The new NXS flatbar shifter looks more robust and I like the little "BIT" buttons you can hide under bar tape. I'm looking forward to trying it along with the new servo. I like to tinker so this is right up my alley. If you're a plug-and-play person, best stick to Di2 or eTap AXS.