For me, running PT 6 on a G4 dual 1.25ghz on OS X 10.2.4, it DOES ask for a confirmation when I try to delete a track with regions in it, as it did in previous versions. It acts exactly the same as it did before. I've got a screen capture of the dialog if anyone wants me to email it to them. Looks much as it did before. Perhaps it's a Preference now, not a default unchangeable setting. Try looking in your settings somewhere to see if the warning is turned off.