
Yes, you can program and reprogram but what works best for me is making a serious effort to get my chips back. My races do not run over 200 people. I have 2 cat litter buckets painted nicely and have workers watching. The red tag lets you tell at a glance if people have them on right or not or are wandering around after the race with them. I laminate a sheet of 25 Alien 9662's with the fiber reinforcer, then spray the whole thing white with pretty good paint. When that is dry, mask off all but the tip and spray that red. Then cut them out and grind them smooth. There will be a few you have to spray red separately. I program them myself, use a permanent sharpie and do an inventory and replace what few are lost after every race.
But, for accuracy and reliability, it is like Brian says, those skinny legs just let the waves go right through. I can have walkers get within a meter of the line before they are picked up. And that is with side circular antennas at ground level. With those BIG numbers and getting 99+% reads, you could almost get away with no bibs.