I have been going through the same decision process. The options are:-
- Spend the money on a VR3 (doesn't even have to plugged into the loop - just assume constant set point of 1.3)
- Use another constant PO2 computer such as the Cochran or the Explorer
- Find another constant PO2 computer such as the yet to be sold Heliox
- Use tables and a bottom timer
For the moment I have stayed with the last option - for me, none of the computers seem to quite provide the simple interface I want, at the price I want to pay or match the deco profile I get with the adjustable GF settings of the vision computer which I use as the primary computer.
I plan the dives using GAP and have put together a number of set prepared tables for various depths and times. As long as the profile and run time on the tables and the vision computer are similar I just use the vision computer for deco. If anything were to look odd or if the computer were to fail I would go to the tables and bottom timer.
I still keep looking at one of the first three options as a better backup though.