HI chichornio,
I'd say do it! You'd be able to share many parts, and consumables. I ended up keeping my HP Z3100PS after I got my HP Z3200 (both 44"PS models), and I can tell you it's been a good thing to have 2 machines!
Goo luck, and so long for now, Tom
PS: BTW, I did the belt replacement job on the HP Z 3100PS myself and was very confident, but when it came to fire up, it failed. I thought about letting it go, but then decided it would be good to keep it as a spare, so I had HP get it going. It took an HP tech more than 10 visits, and HP ended up replacing almost everything (not the belt though), before they got it working again. What an experience. Amazing to witness.