I have the same system but with the simple BeChronized ProActive transponders and I have been using it successfully for about two years (it was called Orion Ceres when I bought it). When I bought this system I had a lot of problems until I gained some experience and figured out how this system worked. The problem always have been that Orion/BeChronized don't have good manuals on how to use their system.
The main problem usually is the placement of decoder. If You use the default antenna supplied with decoder, You should place the decoder at least 1m above ground and right next to the finish line (at least for ProActive transponders).
The second thing is the loop. If the finish line is 2m to 10m You should run the wire around finish line two times. If finish line is more than 10m then the wire can run only one time. This is what they suggest and this actually increases the hits I receive on my decoder.
You can go through documents on their old webpage - http://www.orion-timing.com/download . Although it is hard to understand a lot of that stuff written in english/french, these can be pretty useful.
If You have any other questions i'll try to reply.