"If' it were me,,

I would question how the warrantee would work. Tractor's already got 500 hours, right ?? 100 on engine, how long is the warrantee on the tractor ? 

It'd suck to still have warrantee on the engine and have them say,, "sorry the drivetrain(or hyd system, etc) is off warrantee, you get to pay the bill". I'd want the warrantee to start at the 100 hour mark period.  It's not like a combine you can simply switch the cutting head on if/when something pukes.

I'd not get hyper tense over a 'reman' engine. Remember there WAS a brand new 'factory built' engine in that tractor and that didn't turn out so swell did it?

World's full of remanufactured engines they're not all junk, just like all brand new engines are always perfect.

Again for my usage, no pto would be more of a killer than a reman engine.