Cochrans are really cool for that reason alone, that they can grow as your diving progresses. The biggest downside is the cost for the setup, the software alone is $300, but it is quite diverse and is the only computer I know of with 1 second sampling.
I'm in the middle of purchasing a computer myself,
It's down to the Cochran and the Vytec (have to wait for it come out to try it)
Problem is the Cochran I want is over $2,000 for the tri-mix setup - However I'll bet the Vytec will be close to that as well.
Anyhow, good luck. If you've got your decision down to those two, I'd say cochran.
JUST MAKE SURE YOU BUY IT FROM A DEALER (they are strict about that, and remember it's an upgradable unit that will last your for years and years to come)