With a few years instructing on Tiger Moths I would recommend do one, then the other and I know my Instructor colleagues at my club would all say the same. Certainly the CFI would and he has 10,000 hours on Tiger's...
The techniques are different (, although to be fair not as much as might be supposed, but they are different,) personally I would get one buttoned up and then do the other.
As has been suggested, by all means switch to tail draggers now and then return to nosewheels after you get your licence. (And some subsequent experience - say c.50 hrs - to consolidate. Certainly we have seen some inexperienced pilots that have struggled to remain competent on either, let alone both.)
I've converted people both ways round. In general the tail dragger guys have better stick and rudder skills, but not much idea about the practical use of flaps, brakes, carb. heat or even a full panel. The nose wheel guys take time to acquire the handling skills, some needing a few hours of upper air work just to get used to having to use their feet as well as not doing things by numbers.
I agree with the expressed sentiments on the need to get an experienced tail dragger instructor.
"Yer pays yer money and yer takes yer choice..."
Last edited by shed loads; 12th Mar 2008 at 10:58.