The Hoffman stuff is interesting. To summarise what I've learnt so far:
The stereo masters have received post production through a limiter, the monos haven't. The limiting is apparently pretty subtle though.
Both stereo and mono are weightier / bassier than the 1987 CDs, which is probably a good thing as the latter sound tinny compared to good original vinyl (they apparently were cut flat, which is not how a master is usually meant to be heard - the final balancing is usually applied at the cut stage and can be significant).
The mono mixes of the first few albums also include the 1960s stereo mixes.
The stereo mixes of the first few albums also include the 1987 stereo mixes.
Tape cuts, splice clicks etc have beed edited out. This obviously is / is not heresy.
Most are reporting significant extra clarity. I'd love to hear them, but I'm not convinced I'm prepared to drop £200 on a CD box set so I'll wait and see what the vinyl brings.
Tony.
(who's Beatles collection is mainly silver-black 70s stereo pressings, so should be pretty easy to beat)