Calling all high round count MP5s.  How does the MP5 platform hold up over time vs other weapon platforms?  

Swap out rollers, barrels, and springs at regular intervals using quality non +p ammo...100K would not be unreasonable.

There’s the well-known NASA MP5 that lasted several hundred thousand rounds.

I'm sure there's a Battlefield Vegas longevity thread around here somewhere...

but its only real weak point is the extractor spring. You can use the .223 extractor spring and it'll last longer. Feeding malfunctions can shorten the spring's life but they usually only occur with bad mags or weak ammo (assuming the mag well and mag catch are in-spec).

Moore offers a M.A.D. upgraded bolt, but I don't think it's worth the money. You'll get years of service from a .223 extractor spring, but I leave a spare in the soft case just in case.

Eventually the recoil spring will need to be replaced, and over the gun's whole life may need to swap in larger rollers but the MP5 has the excellent longevity you'd expect from a military weapon. There's a famous one NASA retired that went through like a half million rounds or something. (It had regular maintenance and parts replaced when necessary, of course).

In comparison to other military SMGs... the UZI probably has a lower maintenance burden, but it's also a less precise instrument.
I've never seen maintenance schedule or longevity data for the UZI and Steyr's MPi 81 but they'd probably be the SMGs to beat.

The main issue is worn recoil spring or high pressure ammo with the wrong locking piece causing rail/receiver damage from the bolt slamming to the back.

Ive heard this reported quite a bit.  How well does the “F” type recoil spring alleviate this concern?

It was a Kennedy Space Center ERT MP5 that fired 571,600 rounds from 1984 to 1990. It was at the point the barrel was completely worn and it would have cost more to replace it than to buy a new gun, so it was removed from service.
Frank W. James, (2000), Heckler & Koch's MP5 Submachine Gun, Pahoa HI.

For stamped sheet metal guns their longevity is quite astounding