I'll never grow tired of watching that video BTW, simply brilliant.
I am also a big fan of that video; in fact, that video is the reason I'm considering buying a Thunder Ranch DVD. My own opinions concur with Clint Smith's, in as much as I've heard Clint Smith's opinion on some things, so I figure my thinking is on the right track.
I like the video. My pistol training has been mostly for IPSC, so tactical reloads are anathema to me; I don't think I would be able to not drop the mag even if I tried.
If you drop a mag in real life, why not just take half a second when the coast is clear to bend at the knees and pick it up? Better do that than fumble attempting to retain if you train all the time to drop.
Now, I hear the average gunfight (self-defence scenario) is 3 to 5 shots total. Is it really necessary to try to retain a partially charged magazine?
Averages are just statistics, be prepared for the worst. Empty magazines are most likely useless for the average defensive shooter....bullets though...you can never be absolutely sure you will never need them.
Second, even if a shootout only expends 3-5 rounds, I'd still reholster with a full magazine. It's just a good habit to ingrain.