Last summer is was "Foretrex or GT-11"; the year before it was "Foretrex or Forerunner"; before that it was "ETrex or Foretrex". This year its "GT-11 or GT-31"... with a bit of luck, we could be onto a new GPS thats significantly better again. At this point, the GT-11's are getting scarce as they are no longer being produced.
One thing that we could say is that the "windsurfing GPS" probably has a life of at least 3 years -> based on the fact that some of us are still quite happily using the Foretrex. If you go for the recommended GPS (ie GT-31), it should last a while.
The Sirf3 chip in the GT-31 is still pretty much state of the art for consumer gps chips and there is no obvious successor on the horizon for a while that I can see.
Likewise, the GT-31 is absolute bleeding edge technology for a consumer type gps as far as speed measurement goes and, given the relatively small market for this standard of speed measurement, is unlikely to be substantially improved upon in the next year or two or more as a stand alone logger.
It is possible that 4, 5 or 10 hz chip units may be adapted/developed for this type of logging. They already exist in some forms but their accuracy is limited by their use of the NMEA file format at the moment, and the need for some clever filtering to reduce aliasing. I'm not confident that anyone will go to the expense of developing these in the direction we need in the near future as there is very little commercial demand for it.
GPS units that transit 'live' results to the internet are being used right now but they are at best about the same standard of accuracy as the GT-31 and cost substantially more. They will probably become reasonably commonplace for high level events in the next few years but IMHO are probably unlikely to be affordable or any advantage as a personal unit, at least for quite some time. I think it really depends on what other sporting applications they can be adapted for to provide the demand and cover development costs.
