Discussion of grating resolution as function of number of grooves, from Christion Buil's page,
see here.
From the formula below, (theoretical) resolution is directly proportional to product of m*L, which is number of grooves, engaged by (converging) beam.
All this above is rationale behind my decision to place the grism inside the back-end tube of my C11... and why I expect better results with this setup.
But first I have sort out burning C11 mounting issue om EQ6... losmandy flange is on its way (I hope).