I've played around with the Light React and Magnetospeed a good bit, and both systems work well. The T1000 is a lot more cost effecient and simpler to set up. The biggest advice I can give there is to do a thorough job of cleaning the back of the target before putting on the velcro. Scrub the steel with a wire wheel or a grinder to get all the paint and rust off, wipe it down with an alcohol wipe, let it dry, THEN apply velcro. Other than that, as long as you ensure the entire body is well behind the edge of the steel, and the clear gel is installed correctly, they work great and take a lot of abuse.
The LRs also work well, but they take a little more effort to set up due to the sensors and light being different units. You still need to prep the steel correctly before mounting the sensors. For matches or group shoots, the occasional idiot will think the flashing light is a bonus target. The good news on the Light React is the light is SUPER bright, and you can tie multiple sensors to one indicator, which is great for KYL type arrays. The brighter light is great for distance, and is visible with the naked eye from much longer distances than the T1000, but both are easily visible at long range even with binos.
LR is still inb usiness as far as I know, they've just lost prominence with the PRS (not sure on NRL) due to costs. When you can buy a 6-pack of T1ks for around the price of one LR set, that becomes a losing proposition for most MDs.