The comment about workflow and style is most relevant. While there has been talk about 3100 vs. 4150, in reality there are many older, and lesser backs that give quite a bit of pleasure. While I’d love a later big back with live view, life isn’t so bad with an older Credo 60. While the live view is lousy, it can be made to work, especially when it is needed for the odd focusing condition. Or chimping. And the files are lovely. Sure for monster size prints, the. Bigger backs are good, even necessary perhaps for huge prints, but for medium to large prints, there are other choices.
Two other key ingredients are as important as camera, back and lens are the tripod setup, and the way in which the camera system works for you. Tripod setup is as simple as finding what works for you, and that you are comfortable le working from a tripod. This may include the right tripod, the right head, etc., and comfort carrying it. Ask around here how many tripods we own, and how many heads.
As to the camera system - well, that’s a tougher matter. While everyone loves what works for them, but what works for one may not work for another. Of the four major tech camera systems - three are pancake style (Arca, Alpa, Cambo) and one is a traditional tech setup (Linhof Techno).Each have their own virtues, and even their own shortcomings, and sussing this out takes time. I’ve experienced three of the four closely, and what was initially important has turned out to be not quite right a couple of times... there are subtleties in the use of each system which is not apparent in the first couple of hours...
As someone noted above, use of tech camera changes not only what you see, but how you work. The recommendation here is to go slow early on, do get your hands on the gear (internet review largely useless), and don ‘t over invest at the beginning. Things will change, and if one happily starts modestly, it’s easy to build over time with increased certainty.