Hi, I've used the Air+ system in a number of backyard races. We have a complete Air+ set that we can lend you if you wish to experiment. Also we will help get you as many SIACs to rent should you wish to organize an Air+ event. I plan on writing a detailed set of articles about Air+ at my blog at
http://sportident.ca in the coming months. In the meantime, here are your answers:
a) Unable to download: This should have worked, even with 580 at your various controls, including the download station. I will experiment and get back to you.
b) Extra battery drain: Not when you're NOT programmed for Air+. To explain: Normally a BSFx is programmed as CTL. To run an Air+ event they need to be programmed as BC CTL (Beacon Control). When the control is a BC CTL, you will drain your batteries faster.
c) See the last para of the SPORTident newsletter (link at
sportident.ca). You might want to stay at firmware 580 for a bit longer...
d) When in Air+ mode, the control does NOT know when a SIAC has punched, because the control radiates location and time continuously, and a SIAC just picks it up. Therefore a SIAC will NOT turn on a control, and you will not have proof in the control that the SIAC was there. Not so when SI-x timing chips use this control the old-fashioned way.
In summary a control in beacon mode will not detect a SIAC, needs to be turned on, needs to stay on for the full amount of time, and will drain more battery. I believe Canada will start using this for the elites in national events eventually.