A fine art inkjet print is generally quite a bit sharper than a lambda print, and that may require a different approach when sharpening for output. At least in my experience. If the prints you are making are grainy, try adding a tiny bit of gaussian blur before printing. Of course, that won't save a very grainy scan.
Personally I've never gotten "grain free" results from silver based processes, nor would I want to. The grain adds sharpness and a sort of bite to a print, and personally it's part of the beauty of the analog process. If you want a more grain free rendering, I would definitely advice you to go digital. The Canon 5D is a great camera, and I'm sure it wouldn't take long before it earned it's cost compared to shooting color neg. If ou can afford it, keep the M7 for BW. There's no substituting the look of BW film, imo.