I think I was a "pro" shooter in the film days - American Airlines, JCPenney, Blockbuster, ad agency work, stuff like that - and I never once needed an interchangeable finder for 35mm.
I wasn't shooting volcanoes or icebergs, just fashion. The highest-level 35mm camera I owned was a Nikon N90s - spent my cash on lenses and lights. I had an 8008s for a backup, and an 8008 with a polaroid back (still own and shoot those, though rarely the polaroid). Used MB10 grips on the N90 and the 8008s. Nobody ever questioned my gear, other than clients saying "nice camera". These days, the kids all want chrome and leather, but the electronic shutter pro--ish-level cameras I've found to be much more dependable and accurate. And when I was shooting, if you showed up for the average major-national-brand 35mm gig with a chrome and leather camera, I think you would have gotten some funny looks.
One of the most outrageously screaming deals on a pro-level camera these days is an 8008s for $25. They're all over the place. Or an N90s for under $100, but the 8008 has that awesome built-in multi-exposure - I used the hell out of that!