I spent about 9 months searching for 8x10 options for MG printing to avoid having any filter in the light path. I gave up and just went with the 6"x6" Ilford filters under the lens and I can say it is working excellent (and I'm using an Aristo W45). To get the quarter steps, splitting the exposure between two adjacent filters works for me.
I think, being able to print in 1/4-grade increments is fine enough. I try to print down to 1/8 of a grade with dichroic heads and sometimes wonder if I'm not overdoing it a bit, but as long as I can see the difference, I'll continue to do it. However, some filter/paper combinations have almost a grade between 1/2-'grade' filter numbers. Then, 1/4 increments become a must.