got my P45+ today, (contax 645 fit) and a few quick notes:
Screen - a real improvement brightness and resolution all up, notably easier to ready type and information. higher res means better clearer type, which is great.
Histogram - now very easy to read with clear R,G,B lines overlay, plus ASA, f stop and speed info right under. very easy to interpret. big improvement and should make for more accurate exposing on location. great.
Output - a definite improvement on my very quick tests. Not a stop like they claim, but for sure less noise at all ISO's. everyone in a blind test would take a + file over the old one at 100asa and above. (takes a more experienced eye to see it at 50asa, though it is there).
all ASA - seems to be about 1/5 to 1/6 more sensitive than non+ back
50asa - an improvement in shadow noise, marginal in mid and high tones
100asa - clear improvement, much less noise. usable as everyday standard now
200asa - substantially improved now an option for acceptable quality work
400asa - big improvement, usable if you really need it (wasnt before)
800asa - for emergencies only...
sharpness. no idea what they have done, but I'm showing slightly better resolution in each test shot on the + than the regular back. why ??
The + back comes with Capture One 3.77, which installed fine - no issues (windows)
this has the + profiles, which seem pretty good, and hopefully will improve as things bed in.
small grumble: they still haven't managed to put a 5cent plastic plug on the Firewire connector like they promised... ack!