Actually the focus on the DF+ is very good, albeit one focus point, in the center. The difference between the accuracy of the DF+ and previous versions of of the Camera, DF, AFDIII, AFDII etc. is significant.
Other things to consider:
The P45+ is probably the best still for 1 hour exposures in CCD, and the quality of the files is excellent as long as you stay in the base ISO to maybe ISO 400. past that the noise becomes pretty harsh.
P65+ and IQ160 share the same chip, Dalsa 60MP, probably one of the best overall chips P1 ever released. It is as full frame as you are going get in MF digital, has excellent dynamic range, and sensor plus which allows use of the higher ISO's with a 15MP output. Downsides are the LCD, which is basically the same as the one on the P45+, (quality of the screen on the Canon 1ds MKI, very limited).
P65 and P45+ both only have firewire for tethering, which means that more modern laptops will have issues as they are mostly USB3
IQ140, has the more modern IQ interface, works with the XF body (with limited features) has very good dynamic range again up to around ISO800. The IQ interface is still IMO the best on the market, still top notch, excellent LCD, easy to see the image at 100% in image preview mode, much faster zooming and panning around the file, so if you are thinking of a tech camera, the IQ140 may be the best solution.
If you go with the P45+, make sure it's using the firmware that will allow you to have 1 hour exposures, as some of the P45+ backs needed to go back to Phase for a physical controller card swap (mine included).
Enjoy your purchase.
Paul Caldwell