Sure, the old 500s are heavy, don't handle all that great and are hard to start. But there really is something about them. My first 500 was an old C model I bought in about 1978, and I was hooked from there. A little later I got a brand new TT500F and loved it - it looked so cool and went especially well. Dunno if it was a Monday morning special but that thing flew. I've owned a few more since then including a genuine ProFab HL500 with real history, but that F model really stands out in my memory.
The best moment, indelibly etched in my memory, is riding along the beach at Rainbow Beach in Queensland. It was a fine sunny day and I was there with a guy on a TT350. We were sliding around and 'chucking monos' everywhere. I had this great wheelie going and my mate was alongside on the back wheel as well. Both bikes front wheels were stopped, we were just sitting there cruising along, and the sun was glistening on the spokes and beyond that the sea was a beautiful deep blue. What a moment!