I used to use 6006/8s back in the days of yore, having used 500 series Hasselblads for years before that. Nice camera, with the built in metering modes/drives etc. Similar Zeiss lens line up to the Hasselblads plus the option of Schneider and even faster flash sync. I would have stayed with them if I could have mounted a P1 Lightphase back to it, but in the end did a system change and went back to Hasselblad. That was about 11/12 years ago I guess.
Although the Rollei was a nice camera, I really enjoyed going back to the 500 series. The ones I'd used earlier with not so good with dull screens, finicky hoods and old C lenses etc. But with later ones, they had ironed out all these annoying issues. I really enjoy the simplicity of them along with the relatively compact form factor and light weight. At shows over the years I look at other bodies, think of changing etc. but nothing really appeals, apart from maybe the HY6. The modern Hasselbald does nothing for me. I don't like rotating the camera, much prefer rotating the back (although a rotating sensor like Leaf would be better still). No practical WLF in vertical mode, I don't like the glass, I don't like the software and there's something about the companies attitude that I'm not so keen on either.
Although some people have had problems with focus, due to back spacing, focus screen adjustment etc. I don't have problems or issues with focus using a P25, it's spot on, although I have just put diopters in the WLF and on the prism to help my ageing eyes. I also have the flip down magnifier for the prism, which is great for critical focus. If I need AF for a run and gun type job, I just pick up Nikon or Canon kit. Horses for courses and all that. Even then, if I don't need AF, I often put Leica R glass on the Canon. I guess I just prefer German glass to Japanese, but YMMV.
The RZ is another option with rotating backs, WLF etc, but They have a lot more bulk to them compared to V series Hasselblad. The other advantage of the V series is there is still tons of S/H out there, relatively cheap, you can still get it serviced and will take most backs.
The negatives I can think of off the top of my head are no built in AE (apart from 200 series, but I believe they have become unserviceable), need for a sync cable from back to lens (I've had the occasional cable problem but always have spare and whilst seeming annoying, in practice, is a non issue). Some of the lenses may not be as good with 60mp+ backs, but I don't have one so can't comment from experience. I'm sure there are more, but again, it comes down to how you work, but doubt any of this is a problem if you like to work slowly and deliberately.
That's just my 2c on why I'm happy to stick with and enjoying using an old classic. I have to say I think Victor did, all in all, a very good job! But as already mentioned, you really need to try out different camera systems, backs and software combos to find out what suits you and your work flow best. There are pros and cons to all of them and it gets expensive to change later on. Good luck!