It's harder to maintain stable parameters in a smaller tank and you've already mention that. However there is an advantage that is its easier to do water change. I find that when nitrate goes too high (over 40ppm), there's going to be some nitrate in the substrate so if you do a 50% wc your nitrate won't come down to 50%.
I've used fluval nitrate remover in my shrimp tank with very good result. One third of a bottle gets my 10g from 40+ppm to about 5ppm in a matter of hours and shrimps are just fine. You can recharge it with salt too so it is well worth the investment for emergency situation like this. If you around you should find it under $15 a bottle. I pay less that that even in Canada where everything is much more expensive.