Jim...
Along with Don, I have given info to a number of guys that self built, sold a half dozen outright and sold and installed a few more. Other than using a manual switching system instead of the digital switch and relays, no other changes have been made. No changes have been made (by me) on the box design.
So far, no complaints. Mostly good reviews, similar to those by Don. Even better news: No motor failures that I am aware of. Most of my sales have been to commercial shops.
Since 4 of these motors (I used the 240V LH-7123) cost less than a new Fein, consider the advantages of over 400cfm. The 240 V versions use half the amps, have more power and generate less heat. Vacuum is like money; you can never have too much.
I am sure that is not impossible to pick up some debris, but if care is taken to clean the tubing and a fully adhered spoilboard is used, very few that I have seen use a filter. That said, no one could argue that it is a good idea.
