I make my own re-usable tags in the style if the ART ones, annd us an 8 port FX9600 connected to a 4m / 8 antenna Feibot mat, usually with the end sections turned up to act as side antennas (I do this mainly as I usually only need 3m wide finish line) - I get pretty much 100% reads.
At the begining of the month I had 679 finishers at an event that I needed to review the video of the finish line (for an unreleated reason) and I was able to tick every finisher with no misses.
Incidently later in the day I had a couple of tags were handed in by marshals, they were dropped by runners who had not pinned them on correctly - which underlines the benefit of wearing 2 tags, as they both recorded a finish time with the remaining one!
I have had the occaisional missed read in other races but usually it can be seen that the runner did not wear the tags in the prescribed manner.
I couldn't be more pleased with my setup!