Sorry guys, looks like I missed that post.
Arm sweep is pretty useful, but it changes a few things all at once. It changes the angle of the inner hinge pins in relation to the center line of the chassis (kinda like this: \ /) , and as a result it shortens the wheelbase, and changes the steering geometry as well. If you want to isolate all the other changes it does, you'll have to change your ackerman and wheelbase accordingly. To be perfectly honest, I never do that...
If you weren't going to change anything else but the front toe block it would do as follows: Adding arm sweep will make the car enter the corner a tiny bit smoother, and create a noticeable increase in steering at the apex/middle of the corner. When you take arm sweep out, it makes the car turn in a little bit crisper, but have less steering in the middle of the corner.
Hope that's a better explanation than what you have received in the past.
-Korey