I've been using iterations of the Mamiya/Phase body since its release with the first generation 645AF (is that about 15 yrs+?) and now currently on the Phase DF. I've used the 645AF, 645AFD, 645AFDII, Phase 645AF, and DF; I've owned the Kodak 645M, Phase P30, P45+, P65+, and IQ180. The latest Phase bodies were a bump up in build quality compared to previous Mamiya generation bodies.
I've found the Phase DF to be a very reliable and stable platform.
Battery drain was indeed an issue early on old generation bodies (remember that 1/2 battery sign meant you could just finish your roll of film?). The release of the Phase 645AF/Mamiya 645AFIII really addressed this shortcoming. It's been undetectable on the DF.
I have not detected any battery drain with the Phase DF body. There were indeed power issues early on, causing frustrating lock-ups but these were addressed by various firmware updates and especially by shifting to Energizer lithium AAs---and finally with the release of the EJJI lithium body insert, which imho, put any sort of power issues to rest. If only the Phase MFDBs had the reserves of the EJJI/Phase lithium camera body battery!
Again, there were early frustrations stemming from power issues, compounded by trying to find the right combination, or rather getting the right new set of firmware updates to work together---that meaning,
new firmware in both the camera body and new firmware on the MFDB. This should be a non-issue now.
The EJJI/Phase lithium insert has ridiculous amounts of reserve power. If your DF is requiring constant recharging, I think there is a larger individual camera issue that is not representative of the whole.
The point being here for the OP is that I would not worry so much about differences between the DF and DF+. The largest difference (if it is to be noted) is slightly better AF and the ability to tweak the focus on the DF+. I did not find these additions to be worthwhile to upgrade my DF, particularly without a Phase One "trade-in/upgrade" incentive. Too little improvement for too much cash, even in Dante's Forum.
The DF/DF+ is a stable platform albeit long in the tooth. Looking forward to the new Phase camera body in a few months!
ken