Inspired by Daves wonderful gift, I worked out some timing in my schmatic program (with snaps). It looks to me with 5uS interupts, I will not miss a single step. I will strech them sometimes and shrink them sometimes, but thats no problem. And I still have 40 instructions between interupts. Well prolly more like 30 when you account for the interupt handler itself.

So I think I am off to the races now!!