Over the past four or five years, I've switched digital medium format systems *seven* times. I've basically flushed a not-so-small fortune down the toilet getting to the right system for me. The upshot of that experience?
Using the right gear for the right job.
Of course there is subjectivity in that, and while there is certainly room for personal preference nobody would seriously choose to fight a forest fire with a water pistol. Put another way, if you feel you've got the wrong gear for the job, yes, gear matters a whole helluva lot.
Once you've solved that problem at least to a sufficient degree, your gear does not get in the way of your creative vision or business needs, then the world is different, and you have much more ability to focus on the tasks at hand.
I've learned that this is why it is very important to handle and use your prospective gear before you buy, as ergonomics and performance vary *much* more widely with medium format than they do with small format.