I am one who has opted for TLR instead of SLR for 6x6 format. I have a Mamiya C33, a C220, three lenses (65, 80, 180), a prism, and a type 2 Paramender, as opposed to a Hasselblad and all the trimmings (or SQ, etc.). I have spent $550 on the entire setup. I have also spent $200 on service, so $750 total. I am totally happy with it.
In the studio, I find many of the advantages of an SLR to be minimized, because there, I have plenty of time and plenty of control.
I don't need interchangeable backs in the studio. (I need them in the "field", when I am shooting architecture or landscapes, at the mercy of the available light, on the go, in a rush, in totally unreproducible, uncontrollable situations, and may be shooting only a few frames before I want to change films.) With a TLR in studio, a backup body is fine. When shooting a person in the studio, I will go through a roll of 220 fast enough to change films, if I get that itch (though I do not often get that itch).
I don't need a million different lenses from which to choose. Seven choices for the Mamiya C series are fine. (I would like to get the 250, however.) I am extremely pleased with the quality of the images from these lenses. I do not need nor want the coveted Zeiss Hassy glass. In fact, I prefer the subjective aesthetic qualities of these lenses to those that I see in my friends' Hassy prints.
Adjustment for parallax error is not an issue for me. I have the Paramender (which cost $100 out of that $750) when I need it. If hand held (which I do sometimes with flash), I use the line in the viewfinder. When I am working close enough to warrant an extremely precise parallax adjustment, I am not shooting people anyhow.
I do not often use depth of field preview on any camera in any format. I find it useless 95% of the time, personally. I don't miss it on any camera that does not have it. If I really care about being super finicky about depth of field, I will use a view camera. When I choose not to use a view camera, I am choosing to do so to gain certain advantages, while opting not to obsess over other ones (such as D of F or the way out of focus areas are rendered). Otherwise, I can figure out what I need to figure out without D of F preview.
I also have an RZ, which I use in the studio when I want 6x7 format. I honestly do not find using it much different than using a TLR, or any reflex camera, for that matter. You put film in the thing, you take the lens cap off, look through through the thing, you shoot a pic, you advance the film. I do not find using a Hassy all that different than using a TLR. You take a pic, you wind the advance, you get a square pic taken with a reflex camera. Whether the advantages of a Hassy will help you is up to you, and must, of course, be balanced with budget.
I use my RZ mostly for the aforementioned outside stuff, for its extreme flexibility with backs and such, though I do use it in the studio if I want a 6x7 piece of film. Yes, I do find enough of a difference in image quality between 6x7 and cropped 6x6 in the prints I make to warrant using 6x7 sometimes just for the raw size.
I do not think that any of the quirks of any camera system are things that must be "put up with". Cameras are chosen by us, not forced upon us (most of the time). 1. If you want a camera that has certain features, then get that camera. 2. Don't get a camera that lacks features you want. End of story.
So, decide what features you want/need, based on what you do, and then pick the camera that has the closest you can get to those features within the budget that you have decided suits you.
The OP is already comfortable with TLRs, and sounds like he is on a somewhat tight budget. As such, the Mamiya TLRs are definitely worth looking at, alongside several other camera systems.