I still wear my Gear S every day and still love it, but will likely move on from Samsung as well...
I am still on my international version Note II, and BT and remote connections between it and my Gear S were broken through a Gear Manager update in the beginning of the year. I now use my Gear S in stand alone mode, completely disconnected from my Note II, which means I am missing a ton of functionality. My main use is for it to track my trail runs via GPS, which it still does awesomely ever since last November.
I will also not purchase the new Note nor S for the same reasons you stated: The non replaceable battery at such a high investment price, as well as no SD card slot. I may try out the Gear S2 with my Note II when it comes out, but will likely hold on to the Gear S and upgrade to the next smartwatch that comes with stand-alone phone functionality and GPS and does NOT require a high-end Galaxy phone.
I really can't stand Sammy's practice of selling phones only through carriers in the US with a bazillion versions of software, which in turn can break some functionality when you least expect it, just like it happened to me. Everything was fine between my Gear S and Note until some stupid upgrade. I also despise the fact that a watch would keep me hostage to a brand of phone.
My next phone will likely be an iPhone or Nexus phone, despite their current gigantic sizes (I gave up waiting for a truly small flagship device at this point), because I really, really want something vanilla and which is always up to date regardless of my current carrier, plus the only reason why I ever considered suffering through the horrors of Touchwiz again was the SD card and removable battery anyway.
In short: Until the Note 5 announcement, I thought I would get the Note 5 and the Gear S2, despite not being 100% happy with how they support their devices and break functionality in my case. The annoucement really made me rethink and change course.