I think with or without the "squeak-free" bushings, they will still squeak after a while. For example, I have the "squeak-frees" but they squeak once in a while. Quite bad actually if I don't grease them.

I used lithium grease, and I have no problems. I typically have to re-apply after wheeling because I tread through lots of water, but other than that it's an easy fix.