On a whim, I picked up one of these babies a while back. It's a pretty brilliant concept - a molded-plastic barrel that replaces your regular one and renders the gun completely* safe for dry-fire. Like everything, the training barrel is a mixed bag.
The good news is, of course, that dry-fire is noticeably more idiot-proof. There is certainly still some risk - for instance, since the barrel is not visible from the rear of the gun, it's entirely possible to complete a drawstroke thinking that the training barrel is in when it isn't. It does add another fence to jump over, however, one that requires a field strip to traverse, and the training barrel is painfully conspicuous from every other angle - and it protrudes several millimeters from the muzzle. This allows completely* safe practice of draws, speed reloads, tac reloads, trigger pulling, and such. Trigger manipulation seems unaffected. I had a small bit of trouble
The downsides...one, there is no chamber. While this is of course a feature instead of a bug, this means that malf clearance practice isn't going to happen**, and unless you use a Blue Mag you're not going to be able to even run immediate action drills. Furthermore, if you're unsettled by the prospect of extended dryfire without a snap cap, you're SOL. The ideal would be a setup like the Glock 17R (3rd gun down - bandwidth and ooh shiny warning) - a completely functional gun, but the slide lacks a striker port and the barrel is actually a piece of steel drilled perpendicular to the bore; even if a real round ended up in there, it couldn't go off, and if it did the explosion would be vented out ports drilled in the chamber. Not likely to justify that sort of expense, of course...
* No Such Beast.
** Actually, it's type 3 (doublefeed) practice for goldfish. Hey, a doublefeed! Tap-rack-noclick-lock-rip-rack-rack-rack-load-hey, a doublefeed! (repeat until you run out of dummy rounds.)