I have a BeamHit 110 system (basic electronic laser target and laser transmitter.)
I upgraded to an LT-500 laser transmitter at the time of purchase. The advantages of the LT-500 over the standard laser transmitter are that it requires no zeroing (it is precision-aligned to the bore) and that it is less bulky (you can practice presentation from the holster.)
The TR-700 target is camera tripod mountable, lending much flexibility to target placement and height adjustment.
The laser pulse is in the visible range, producing a momentary red dot on the target surface. You could use the laser transmitter without the electronic target, but I'd just as soon dry fire without the transmitter. The target, though simple in operation, does add an element of challenge that regular dry-firing lacks. Tends to keep you honest with yourself, too.
Neither transmitter comes in physical contact with the firing pin. Rather, the impulse of the hammer (or striker) contacting the firing pin travels down the barrel and is picked up by the transmitter. I always have an A-Zoom snap cap chambered whenever I use my Beamhit--It does not impede the system from working at all.
Both the target and the transmitter are easy to set up and use.
Materials-wise they are pricey for what you get, but there aren't really any competing products that meet or exceed the BeamHit systems for a lower price.
The 190 PMTS looks like a neat system, but it requires a PC running Beamhit's software to use. Although it appears to have its advantages (record of group size, for instance), I decided to keep things (relatively) simple.
I am happy I purchased it, and have no doubt that I became a better shot by using it.