6.0 has been perfectly fine for me, aside from getting a few add-ons up and running.
Now 4.0 was f***ing awful. Didn't even try 5.0.
I had to laugh when Chrome failed to properly pull up the maps for a website because it couldn't load a Google link when FF was perfectly fine.
--
"One toot on this whistle will take you to a far away land."
-Toad, SMB3