I should have got here sooner. My specialty is neos. It's about all I have worked with for the last several years, and have lots of tanks. (I forget at this exact moment how many.)
SS gh will be just fine for your neos. SS gh/kh will be fine, too. Both will work. I've done both and haven't seen any difference.
As far as TDS, I've seen people keep neos in 1000+ TDS and they bred fine. Neos are the TANKS of the shrimp world. Meaning they can take a lot and still survive. I've personally kept them in anything from 150-600. I've experimented a lot to find the sweet spot for me and my water, location, etc. This year I've tried 150, however I think I've gotten better breeding at 300-400, so I'm going back to that again by the end of the year.
gh for me is best between 6- 12. Below 6 and they tend to have problems molting for me and die off.
As far as changing TDS, I don't have any problem raising it instantly. However when dropping TDS, I have a rule that I don't drop any more than 100 TDS in a wc for neos. 50 for more sensitive shrimp. By reducing the TDS, it sucks the minerals from the shrimp bodies which can be hard for them until they adjust.
If using RO + SS, I find the TDS of the gh I like (1 gh very roughly equals 20 TDS) and just mix to that TDS from then on.
Hope this helps some?