410/510 and 750/760 were state of the art when they were new, it's just the art has changed.  They were unarguably a step above anything else on the market when they came out.  It's just everyone else learned and caught up.

On our first date I took the young lady I eventually married to the MF dealership to see Dad and Gramp's new 750's setting on the lot waiting on delivery. You can't say she wasn't warned.

Cousin who farmed with us several years had a 760 with a 20 ft head on it.  One year we were caught up and the river was coming up so he and dad went to help a neighbor with a couple frog colored machines.  Neighbor called his guys on the radio and asked if the red combines could keep up.  Charlie replied "He** we can't even see his smoke he's so far ahead of us"

750 was a good combine, a bit difficult to work on, parts were too expensive, and they were not worth their weight in scrap iron in the mud.  In small grains I would put a properly adjusted 750 against anything on the market today for a clean sample.