FWIW... the final outcome here is that while DSLR scans will be my main thing for smaller formats, I found a refurbished Epson V850 from Epson that with 1yr's warranty and another $100 for extension, offers 2yrs of service. Decent price for the scanner at $699. Since this machine does a decent job and 4X5 is basically one scan, I'm not sinking a lifetime into this and that works for 4X5 where the prospect of stitching scans of a negative WITHOUT the luxury of either a pixel shift camera like the Sony A7R4 or a geared copy stand table to shift the image seems a bit daunting. Looked seriously at used V750's of various stripes and they were roughly the same price but without the improved film holders of the v800 series. With the Betterscanning folks AWOL... at least for now, this makes a difference.
As a side note, let me add that Epson's Clearance Center hiccupped on my order yesterday: It was there and then it wasn't. I called, but all they could say was they saw my order but it must (now) be out of stock. Yes it was... because the system went wonky. Randomly, I went back to the site this morning and there it was. So if you're ordering from Epson directly as I did, let me suggest: 1) create a log in - don't try to purchase as a guest even if you're going to use Paypal (which I did); 2) be persistent and cross check when your order goes in that you payment account has been charged and you've received a confirmation email from Epson. This is how I discovered yesterday's order didn't happen. And by contrast, today I logged in to Epson under my credentials for the site, placed the order and it went through with confirmations galore. Lesson learned.