Certo6 appears to do a good job fixing up folders. I think a TLR is more practical though, and I have two TLRs (yashica and rollei, not that it really matters, and neither of which is worth more than $250) I have used but not owned medium format SLRs, so listen to others regarding that; pentax 67 series is a respectable option too.
Good tones come first through good film developing and film. Consistency in mixing, temperature, and agitation so as not to over/under cook things. I really like 12 shots per medium format rolls. I'd scoff at 12 shots per 35mm roll though. I mostly use tmax400 in pmk or pyrocat hd for film/developer. If you change films all the time you won't figure out good tones.
In the darkroom, if you don't have a el-nikkor/rodenstock/scheider componon-s enlarger lens, you might spend the $50-100 to upgrade. Final results of the tones depend on the output paper as well. A good paper won't make a bad image sing, but it can make the great images even better. Tastes differ, but I'm liking alternatives to normal B&W vc rc such as ilford mg rc warmtone, ilford art300, fomatone mg classic.