WRMC purchased their system for RFID tags approximately 7 years ago. They have a combined use for MX, Harescramble and flat track races. It uses Motosponder software, and as already been stated here, is not compatible with the MyLaps software. I believe the total cost of the entire system was somewhere in the neighborhood of $10-12K. There are a number of members who work at a local label business and can get the RF tags dirt cheap as well.
Mud will not have any affect on reading the tags, but issues are with particular type of helmets (carbon fiber, reflective material, etc.). The software is not updated as often as a mainline product such as MyLaps, and is a bit cumbersome to use, and a bit outdated.
With MX races, it is easy to use, with only a couple of readers set up at the finish line. You have to "build" a race order in the software, and then it will also tell you if any riders are in back-to-back motos so you can rearrange that. Since it is not compatible with MyLaps, Connie then would have to build her own race order in MyLaps in order to do the scoring and print out results. It is possible to do the same thing with the Motosponder software, but takes longer and is not as pretty looking. Nowadays with Connie bringing the OMA's kiosks with her, it is much easier to just use that system and handscore. WRMC has just been using the MyLaps for MX the last couple of seasons, and not setting up the RF system.
It is quite beneficial to use the Motosponder system with flat track races because you have multiple riders crossing the finish line within microseconds of one another. This takes out all of the guesswork with scoring. Problem is, even using four readers, every once in a while it misses a rider or two. Someone sitting at the computer can hand-punch that rider going by the reader, if they are paying attention. With flat track it gets a bit nerve racking to keep paying attention every lap of every race just in case that happens.
It is also beneficial with hare scrambles because you can look at lap times and determine if someone if cutting the course (not that anyone would ever do that).
The system is a thing of beauty when it all works correctly. Laps times are available, and can even be output to a monitor to view, or read it on your phone. With WRMC, like most clubs, only a small handful of members are familiar enough with it to set it up for each race. If that person is on vacation, or unable to attend the event, it can't be set up. With WRMC's system, it can't be permanent, because it constantly has to be moved for different types of events.