I'm not familiar enough with these blowers to distinguish one from the other. Here's my take:
The Pronovost is heavier than the LuckNow which can have its advantages and disadvantage.
The Pronovost P680 looks to be in very good shape....somewhat better than the LuckNow. The P680 is newer... about 10 YO as the LuckNow is 30 YO.
The price for the Pronovost is $1600. ...the LuckNow is $1250.
While both will do the job, I chose to go with the Pronovost because my sense is, with it's condition, it will probably need less service/repair in the near to mid term.