all-purpose cycling computer
I'm looking for a cycling computer that can be transferred between bikes (road and tri), be used outdoors and on trainers (roller and resistance), measures heart rate and cadence, is wireless and could measure power that is compatible with SRAM Red and Zipp cranks and not measured at the hub since I use different rear wheels for training, road races and TTs. Any suggestions?
Short answer: no.
Slightly longer answer: You could get most of that except the power from several odometers. You need to swap cranks or hubs to get an acurate power reading, therefore invalidating your requirements on not swapping hubs or cranks. Some trainers can give you power numbers, but that's useless when you're on the road. Pick your poison, either build up a powertap wheel or get an SRM.
Or, just get a wireless odometer with HR+cadence which can work off the rear wheel, and live without knowing your watts.
It's ALL base...
If you're willing to forgo the SRAM and Zipp cranks, you could use an SRM power meter with Garmin Edge 705, with rear wheel cadence sensor and magnets mounted on each rear wheel. http://www.srm.de/englisch/prod_srmts_str.html
The Cinqo Quarq is an option for SRAM cranks, with the Edge 705... http://www.quarq.us/Spiders/CinQo.html
Get out your money gun, and start shooting!