A couple of points not mentioned already:

the service tech didn't tell you not to use an extension cord - only that if you want "full power" a direct connection is preferred. You can read all about voltage drop here on the creek.

"you should never have this plugged into and extension cord if you want full power. It must be plugged directly into the wall outlet".
- 100 yr old poplar is going to be much harder than new birch.

- The hitachi saw you mention has 600 more watts of power than the festool. That ain't hay. Coupled with the fact that the standard blade for it is a 24t , and it's easy to see why that cut better than the festool. It was better suited to the job.

- re: a lemon. It's possible. You burnt up the motor, period. Using it incorrectly certainly contributed to that. I'd be more concerned that the electronics didn't work as advertised.

Burnt motor = new armature. New armature gets new bearings from anyone seasoned in their replacement. The alignment was worrisome, could have been from the factory that way which isn't good.

I would say that it is "nice" to have different blades for different jobs, but with high end equipment, that shouldn't be necessary.
With more experience you'll learn this is often not the case. Big ol Italian bandsaws are popular around here, especially for cutting veneers. They are high end and expensive. But if you put a 6-10 tpi blade on one and try to slice veneer you'll have problems and won't like the results. And. it'll have nothing to do with the saw. Try crosscutting or cutting a curve with a blade suited for veneers and you'll also have a disaster. Not the saw's fault.