Why P45+ have a 60min. Exposure time & Other Back have 1min or less. I didn't know what is the difference from Technical wise.
I have both P45+ and P65+ backs.
There is a lot of fuss in forums about the long exposure issue. In my view, it is only an issue for VERY specific types of photography such as shooting star trails and shooting moving water to make it look smooth. Yes, the P65+ is limited to 1 min exposures, or sometimes less here in the Middle East in summer. As the sensor heats up, it produces "noise" in the shadows. If you haven't seen this before, it looks kinda like film grain but rougher. Software can smooth it, but often at the cost of detail.
In practice, it is mostly a non-issue as digital lenses tend to be optimised around f8 or so, hence the long exposures necessary when shooting at f16 or f22 rarely happen. I shoot most of my work either in the last glimmer of sunset or after dark (I am a pro architectural shooter) and have only had issues with noise once. Also the latest version of Capture One Pro has much improved noise suppression controls.
Cheers,