Allen, yes the Electrolux Epic 6500SR is the same unit. All they did when Electrolux changed their name to Aerus, is change the name to Legacy & replace the double stage Electro Motor they had been making themselves with a single stage Chinese-made Johnson motor. Otherwise, the two machines are exactly identical.
I would strongly suggest before you spend money on ANYTHING that you get your Legacy into a authorized Aerus dealer. Unless you did suck up water, I highly doubt your motor is rusty & needs replacement, it sounds like you just ran into a scam artist that was trying to con you into buying a new vacuum. The fact that your vacuum still turns on & runs, tells me that when you took it apart something got miswired, or a switch might be failing somewhere. Let the people that REALLY know your vacuum have a look at it first.
As for compatibility with your attachments, the Epic 6500SR & it's attachments are a exact match. You could also just find a canister only with a rebuilt or new motor installed & just keep what you have & use with the new canister. Any Electrolux plastic bodied canister, EXCEPT the Rennaissance, Epic 8000, Guardian & Guardian Platinum can replace your Legacy, the only differences would be the onboard tool storage being a clip instead of a rack like the 6500SR/Legacy, & some models won't have the Automatic Control bag shutoff feature. Just take a look at the hose end, you will see those units the machine hose end is identical.
Best of luck getting your Legacy working again.
Rob