I have an old '90 model Morbark 209 with 4.9 I6 gas engine. No hour meter. I'd be afraid to say how many hours are on it.
Last year the radiator (stupid angle mount that catches all the leaves from the chip bed) never got blown out like it was supposed to (prob my fault) and blew the head gasket and cracked the head. I had a buddy with a 86 F-150 same motor, bought it wrecked for the motor for $100 and swapped it in.
No problems outside that. Of course the normal Hyd motor, lines, tires and a set of brake shoes. It was a rental unit for contractors before I snagged it so I knew it was serviced well. Runs every day smooth.... new blades yesterday. Today its eating 8" dia sycamore about 30 feet long off a (previously topped) removal, no auto feed, just feed it and walk away, let it eat. About 1 hour per dump load.
If the ones you are looking at are maintained, I'd not be afraid to go with one of them.
My$0.02
-Ralph