Keeping those early Mk1 hinges seems foolish to me, and most likely based on irrationally giving vintage purism greater weight than practicality, safety of the instrument, and common sense. I consider it malpractice to restore an early Mk1 and keep those hinges. They have no redeeming value.
Well, that's one opinion...
If you got a hold of a very nice condtion pre-'76 Rhodes, would you replace the hinges straight away? I sure wouldn't. I can understand putting the later, more stout hinges on an original condition piano, as they do have better function. However, I find them to be rather ugly, and aesthetically little better than a door hinge.
Some people prefer having original equipment on a vintage piece of gear. As a guitarist, I certainly do, even when "better" replacement parts are available. For example, the Danelectro guitar bridge. Crude, and in some ways an intonation compromise, but anything other than that piece gets into Frankenstein territory, and takes away from the charm of a vintage piece.
But if I were going through the trouble of "restoring" a piano, I'd prefer to keep as much original as possible. Because such a piano, in my world, would be the "set it and forget it" type. I wouldn't play out with it. That's what worn, but well serviced pianos are for.
Also coming from the car world, I see this more as a matter of restoring vs. customizing, or hot rodding. All cool, just different.
That the hinges should be replaced is an opinion. That the early Mk1 hinges cannot perform their basic function without being damaged is a fact. They're stamped in such a way that there's a gap behind the plate, so you can't even tighten them down without damaging them. I've never seen an early Mk1 hinge that wasn't bent up on the case side. In the past, I've fixed them up, and they just get bent up again. A part that cannot perform its basic function is junk, and the early Mk1 hinges are junk.
There is no guitar equivalent, because guitars are not their own case. The hinges do not affect sound in any way. The hinges are a purely functional/practical component (with some aesthetic effect). They are a functional component that cannot perform their only function.
Yes, any piano with those hinges I do for myself I would (and have) change out the hinges straight away, without hesitation. I build for two people; myself and the person who will own it in 30 years. No way am I going to leave a part on there that I know will fail immediately even if I fix it. Some people may look at those original Mk1 hinges and think 'oooh, original!'. I look at them and see a woefully inadequate piece of crap that can't do its job. I would not go through the trouble of restoring a piano and leave doomed-to-fail junk on it. We've had 40 years to find the weaknesses in the piano and figure out better solutions.
Leaving the original hinges on because it doesn't leave the house anyway is like leaving a transmission that flakes out in 4th gear in a restored car because you only drive it in town anyway.
The 'restoration' vs. 'customization' argument is bunk. You can customize without restoring, you can restore without customizing, you can restore and customize, etc. And where does one draw the line? The repro Tolex isn't an exact match to the original, so if you re-Tolex, is it then a 'customization' by definition? As far as I'm concerned, restoration means restoring to returning the instrument to optimal appearance and function. If one customizes in the course of a restoration, it does not negate it as a restoration. It would probably make more sense to use modifiers, like 'factory original restoration' and 'custom restoration'.
I'm currently in the final stages of restoring a '55 Bel Air 2 door hardtop, and though much is original, it has 4 wheel disc brakes and power steering. Why? Because 4 wheel drums and no power steering sucks. Just like a crappy hinge that gets bent when you try to use them sucks.
But, as always in the end, to each his own.