Rode a ton of them brand new, it was my job. I would uncrate a group, 4 or 5, and have them ready to run by quiting time at 6. The next day I would spend a good amount of time doing test runs, doublechecks and a good cleaning before putting them in line to be sold.
As said, a proper rebuild with quality parts will be just like a new one. I rebuilt my 94 XP, motor, pump, driveline, plus tweaked the carb settings and changed to a shallower pitch impeller and I'd say mine runs better than the day I set it up for it's first owner.