Just how sensetive are OEBT shrimp and Cherries?

Anything other than 0 ammonia, 0 nitrite and >20 (preferably 10) is bad. Your RCS will probably make it, but I wouldn't put money on the OEBT. Get yourself some Prime or AmQuel+ to detox the ammonia and nitrite until your cycle settles back down.

-Lisa

I haven't kept OEBT, but RCS are like roaches. They'll survive a nuclear bomb, if it doesn't have copper in it.
Seriously I had a tank I started for RCS and had to move them in quick because other fish stalking them. It went through an ammonia spike, and a huge and very long nitrite spike (>5ppm for a week or so, with water changes). I only lost a couple out of the 20 I had, and now they're right as rain. If the water quality gets bad they'll start to lose their color a bit, so watch for that. Now that my tank is settled they've all colored up nicely.