nortexoid kinda hit it IMO. I personally like the 900NF better because of higher specs and most importantly, it's a aperture grill meaning better colors. It is more flat too because the 900IFT dynaflat tube is not perfectly flat just has a flat piece of glass over it.
But if you're a person who prefers shadow masks for their crisper text (generally) or because the AG lines bother you, then go ahead with the 900IFT.