I just bought a powertap!!

I bought my PT in 2006 and in 2008 had issue with hub and had to buy a new hub at great discount as they no longer had parts to fix mine which meant I went from a wired to wireless system.  In 2009 I got a Quarq. I use PT on trainer as my trainer wheel and will be using it with my new 150 cranks.

Customer service is great and they are super at problem solving.

Question for you Kathy and any others, I'm considering either the Powertap, Quarq, or Stages. I do want something I can swap between bikes. I think I can easily with all three (PT would use a wheel to swap).  A friend just told me the PTs were a pain and had a lot of issues compared to Quarq and Stages. 

Any ideas?

I've had my PT for 4+ years and my wife has had hers for 2.  Zero issues with either of them.  Change the batteries in them once in a while and they are happy.

I've got two, one on a training wheel I bought used, and one on a racing wheel. Only problem I ever had was not being able to find that plastic tool to change the battery.

Use multiple bikes best choice is something easy to change which for me would be PT or perhaps the new pedal based systems.

Using multiple wheels on same bike, I'd go with crank based system like a Quarq.

I know some folks who are good at mechanical stuff can change quarq from one to another bike  in 5 minutes but that is above what I want to do on an ongoing basis.

I put about 18k miles on my PT before going to a quarq and gave the PT to my GF...which she is still using.  I have never had to "baby" it...I used it in wet weather and washed my bike without thinking twice about it.

As for the other question about swapping PMs between bikes, I would say as long as everything is compatible, they are all easy to change.  I swap my Quarq between my road and tri bike all the time.  I've also removed pedals before so here's how I would rank the ease of swapping.

1.  Powertap being the easiest.  Takes literally less than a minute with no tools required.
2.  Likely Stages assuming you already have the drive side portion of the crank on both bikes and are just swapping the non drive side PM arm.  My guess the swap would take about 2-3 minutes, and maybe 1 minute if you were in a rush. 
3.  Quarq would be a very similar process as the Stages swap, except you simply need to pull the drive side of the crank out from one bike and put it in the other bike.  That process is as easy as it sounds...pull out and put in.  Maybe an additional 30 seconds.
4.  This may surprise people, but I would rate swapping pedals as the most time consuming swap.  It requires you to remove 2 pedals, and 2 pods (receivers), then put back on 2 pedals and 2 pods.  That's 8 separate steps.  If you read DC rainmakers reviews on the Look power pedals and the Garmin Vectors...he also shows that the installation process isn't super simple.  Probably something you can get good at over time, but far from simply untightening the pedals and tightening them back on to another bike. 

Golden Cheetah. It's free and works well. I don't think you're watts will be exactly the same indoors and out, but there shouldn't be that much of a difference, power is power. If anything, I've noticed I feel a little stronger outdoors, probably because I'm moving and not sweating puddles. I definitely think it's easier to sprint to higher power outdoors, but I've also done a 20 minute TT (ok, it took 22) and the power is fairly close. In my opinion, it's easier to get a structured workout on the trainer, but I have a hard time sitting on it for more than an hour and a half. Plus you're not working on bike handling. So long rides and group rides outdoors are fun and take care of those needs.