@OP, you really should send the lens in for calibration.
There is a general trend in Canon cameras- the later the model- the better their AF systems perform compared to earlier models in the line. It should not surprise anyone- with every year that goes by, the engineers continually research how to make their AF systems better, faster, and more accurate.
The 60D has a good reputation for fast, accurate autofocus, despite the lack of MFA.
I used to have a t1i.. Moved onto a 7D- compared to the t1i- it was fabulous- night and day difference. The move to the 5D3- wow.. It seemed more accurate than the 7D was. Got the T4i- and even that seemed more accurate than the 7D was.. Should not be a surprise either- both of the newer bodies- were newer by a few years... Reality- the bodies are probably just more "normal"- closer to spec than what they were making years back.. You may very well find that moving to a different, newer body- might work better with your lenses- MFA or not. For just the MFA feature- I think I would send the lens in for calibration otherwise.. If I wanted the other features - all cross type AF points, larger body, better viewfinder, more controls, .... - then switch bodies.. And then try your lenses on it- send it in for calibration if you need to.. But if my only thing was MFA- I would not upgrade the bodies- especially for a single lens.
With any body, if your output is jpeg, adjust your picture style by bumping up things like sharpening, contrast, etc to your liking within the picture style itself.
I would suggest buying a body based upon what features you need or want , but I would also temper it with a bit of sense as well. What would a 7D give you over a 50D ? Faster FPS. Slightly more megapixels to crop from if you need it. Slightly better low light performance. More AF points to select from.. More modes for AF selection.. Video features. If you find no features that you care for- heck- save the money- and go for the 50D. I am not sure which CF cards the 50D supports up to- so you will probably want to find out before you buy the too big of a CF card though. .. Personally, I've never used larger than 32G on my 7D though.
EOS 5D III, EOS 7D,EOS Rebel T4i, Canon 70-200 f/2.8 IS II, Canon 24-105L, Canon 18-135 IS STM, 1.4x TC III, 2.0x TC III, Σ 50mm f/1.4, Σ 17-50 OS, Σ 70-200 OS, Σ 50-500 OS, Σ 1.4x TC, Σ 2.0x TC, 580EXII(3), Canon SX-40, Canon S100
Fond memories: Rebel T1i, Canon 18-55 IS, Canon 55-250 IS, 18-135 IS (Given to a good home)...