One of the challenges of a search like this is you don't know what you don't know. So I'd suggest open ended broad questions and providing us more background/context such as
- What kind of subjects you shoot
- What kind of approach/methodology/technique you'd describe yourself as having (or wanting to have)
- What you're looking to improve over your current kit
- What about the practice, theory, and business of photography are most important to you
The advantages and disadvantages of medium format are profoundly different depending on the above. For example if you shot football with long lenses then moving from a dSLR to a Digital Back would be a catastrophic decrease in hit rate, ease of use, and flexibility. On the other end of the spectrum if you shoot still life / product and do focus stacking it could be a several-fold increase in productivity, ease of use, image quality, and flexibility (
XF Focus Stacking Webinar;
XF focus stacking article).
But as to your specific questions:
- Shake/vibration: the least you can get right now is using one of the few systems that have a sensor-based electronic shutter option (ES). But this doesn't work for every kind of subject/scene or style of shooting (it's mostly a tripod based thing). Read more about the
ES on the Phase One IQ3 100mp. When shooting hand held the timing and physical construction of the shutter mechanism and ergonomics of the body are a big factor in minimum hand-holdable speed, as is the question of what is "acceptable" to an individual photographer when it comes to slightly-less-than-100%-sharp images; for example when I'm shooting a wedding with an IQ3 100mp and I'm at 1/125th with an 80mm lens I know that I won't be getting
perfectly sharp images at 100% pixel view, but I also know that I'll be able to make a sharp 11x14 print.
- Capture One handles large raw files
very well. For the bulk of the workflow (e.g. editing, adjusting, zooming to 100%) the speed is the very similar when using 100mp raws as 16mp raws (my reference points since I use both Phase One and a Fuji X Pro 1). Once you leave raw and need to work in rasterized layered TIFFs a 100mp image will become considerably heavier to lift in Photoshop.