If you were planning on ordering a shark guard today then I would hold off.
For today's testing I started with the standard setup of the lower guard with only the small flaps on the width adjustment screws and no other modifications. This is pretty much what most of you have so I though that might be the best approach. I was using my 520 with powerpro and ripping some 3/4" bargain wood about 3/4" wide. I have an L off-set so the guards are not interfered with by the fence. I have the stock table insert. I'm using a combo blade and not a rip blade for the cutting.
The shop vac is attached to the lower guard and running for these tests. Later when I switch to the shark guard I added a "T" to the line and have a hose to the shark guard and to the lower guard. On the final few videos you will see what happens when I run a hose directly to just the shark guard.
For the amount of cutting I did it was amazing how much saw dust was left uncollected. What a mess, I had forgotten how bad it gets.
Anyway after the videos are all up I will post again with links and explain. what you are seeing.