I sent my original post to Saris for comment and this is what they wrote back:

First let me say that I do not know when or if PowerTap will be compatible with Garmin. We have many customers that want it to be compatible, and it is being talked about. I will try to answer your questions in more detail, but again there really are not many definitive answers at this point.

1.) I don't know how long it would take if it does happen

2.) This is a detail that would be figured out once we know if this is going to happen

3.) You do not have to use our analysis software. We have many people that use Training Peaks. We cannot support Training Peaks, but you can easily call them when you have software issues.

4.) This is something that you may want to speak with a wheel builder about. When you want to race you can use the PowerTap as a cycle computer. You would not need a hub because there would be no power, but you could use a magnet on your rear wheel and you will have a cycle computer for racing (very popular thing to do)

5.) We always suggest that you shop at a local bike dealer. If your hub does need support we have excellent customer service We sell many PowerTaps and a very small percent ever come back to us. Your PowerTap would be under warranty for one year. We always take care of our customers. At this point in time we offer upgrades at a discounted rate for original owners. Here at Saris CycleOps we believe that customer is KING!

Let me know if you have any further questions.