My recent experience may shed some light on the truth of the previous advice. Just this morning, my family went out for a morning sail from our home port here in Friday Harbor, San Juan Island, Washington. We sail a Gulf 32 Pilothouse named Aeolus. We were beam reaching in about 10 knots with gusts below 20 when all of a sudden our boom vang popped loose. I went forward to find that the eye that was in the mast track had popped its welds!!

Mind you, we've sailed this boat extensively and in some high winds for the past couple years. I'm just glad this thing popped close to home and in relatively mild conditions.
As a stop gap, I connected the boom vang to the mast pad as was also recommended here. Don't know if it is an ideal place, but it is sure as hell stronger than anything placed in the mast track and subjected to those loads.
If it is truly OK to leave it on the mast pad, I'll do that, and save the expense of some special gooseneck for the boom vang like what I've seen on some other boats.