I tend to run my PCS with the riving knife only, not the guard. The guard and it's dust collection is IMHO good if you are doing a bunch of rips. It depends how you work. My non-thru cuts and trimming cuts make so much dust that even if I had the dc boom, I wouldn't be able to utilize it for these most offensive ops.
If you do not require a mobile base, then I would instead put the $$ into extra brakes. Remember, the dado brake is different from the regular one.
Also, there are reports of people having issues with the thickness of the riving knife and their chosen blade. So, if your blade is not on the same page as the RK, you may want to get a new blade (the other option is to grind the knife).
Also, if you