My Woodworker CNC is due to arrive in 2 days. I also ordered the Suckit pro dust collection. I saw in the description that it come with 2 different height brushes. One is 1" high and the other is 1.5" high. Is there a strong argument for using one size vs the other?
Thanks
That depends a lot on what you’re cutting. If you have hold downs that the brushed will pass over then you’ll want longer ones. If you have deep cuts in a thick board you may want longer ones. If you’re cutting parts out of a piece of plywood and won’t get near the hold downs then the short one may work.
One way to find out if there will be an issue is to set the dust boot to the correct height and then manually move the router around the “known” cutting area to see if there will be a problem.
I generally lean towards the longer brushes as I get close to hold downs and I pocket cut areas where I want the brushes to capture as much as possible. 100% dust collection is… unrealistic but you can always shoot for 99.9% 
Also be mindful of your bit lengths. I’m a new user as well and purchased some shorter 1/8" bits to learn with and moved the router to the bottommost mounting holes so I could cut my waste boards (i.e., the tip of endmill had to reach down to actual workbench surface). While the collet nut clears the hole on the dust plate, the collet lock button does not and will crack the plate if you go that low. For these initial cuts, I ended up keeping the plate removed while still using the dust boot with the 1 1/2" brush. The router was set up this way (i.e., short bit and long brush) because I found the 1" brush almost impossible to install in the track and keep it there. In my opinion, the brush spine material could be a bit more pliable but it could totally be my technique (or lack thereof).
Good advice. I think I’ll start with the longer brush. Thanks.
I recently put my system together and chose the 1". It works very well for what I have done so far, my reasoning was that it gets the suction closer to the cutting surface. The brush was such a pain in the fudging neck (only I didn’t say fudge) to install that I doubt I will ever vounteer to install the taller one. I usually use the blue tape and CA glue method, so no wories about clearing clamps. Just my .02.
I have the longer brush in now but I had to leave the insert plate things out so the router won’t crash into them. It reduces suction a little but still works fine.
I also had to trim some of the bristles that were getting bent in towards the hose connector and trapping sawdust, I didn’t have that problem with the shorter bristles.