Regarding runout on the Dewalt, I had a problem with mine that had me questioning the entire shaft/bearing assembly.
Darn blade would start wobbling the second it touched a tile! Very maddening and hard to get a clean edge to save my life.
Turned out, it was one of the arbor washers turned backwards - that's it!
A little embarrasing to admit, but simple to correct and it cuts nice and clean now.
If you are using a Dewalt with some serious runout, the switched around washers are easy to miss - not nearly as obvious as you would think....
Julian