Okay, I can end the debate. I had originally plumbed my gara...shop to
a Craftsman 6HP (yeah, right) shop vacuum to support one machine at
time dust collection for router table, RAS, and contractor saw with
dust panel underneath and makeshift closure of the back. It actually
worked pretty well, but it was not catching the fine dust as well as I
wanted.

So, I just upgraded to the the 2HP (at 20 amps? That math doesn't work)
Harbor Freight unit. I had anticipated this move when I put in the
plumbing and used 4" PVC for everything, including a convenience drop
in the center of the garage ceiling to vacuum the floor and cars etc.
All I had to do to install the new DC was to add a 4" port and hood it
up with flex hose. Since I like having the availability of the vac, I
left it plumbed in, but added a blast gate to both it and the DC so I
can select which one to use.

It's a perfect set up for a side by side comparison of vac vs. DC.

The results:

- As mentioned above, the shop vac is okay as a DC for one machine, but
not good enough for my wife, whose car was getting dussted regularly.
- The DC works MUCH BETTER on all machines. On the contractor saw, I
could not see anything at all escaping while ripping some Spanish
Cedar.
- The 2HP CD makes a lousy vacuum cleaner.

Okay, everyone already knew this, but it was interesting to see it
first hand.

Tom