Good Evening-

I've gotten so much great information here that I'm glad to finally be able to contribute something. I bought a Ridgid R4511 table saw when they were on clearance at HD a few months ago for $299, and was really impressed with it, except for the fence and rails. After doing some research, I determined that the fence and rails from the Craftsman model 351.221160 were an exact fit, with no drilling or anything extra required. This fence is a huge improvement, as it's Biesemeyer clone with high density plastic faces and dead flat. The guide tube is much heavier duty than the Ridgid one, and is one solid piece, instead of spliced together with a plastic coupler, which for me, caused considerable deflection and aggravation in general. It adjusts for parellism and 90 degress to the table super easily as well. As a bonus, the scale and plastic end caps on the Craftsman tube are separate part numbers, and I didn't figure I really needed them, so I didn't order them. But when the tube came, they were on! I am delighted with this saw now and really think that if it lasts, it will be the last saw I ever really need. This solution is a little more expensive than getting a Shop Fox system, or something else, but I was willing to pay more to have everything all lined up and ready to go, no drilling and calculating and fussing with things.
Hope this helps someone who's considering an upgrade to their R4511!