Thats a tough choice. I've had lots of experience with the '02 era Sprints (though I haven't owned one), and know they are great bikes. Add the triumph carbon fibre can, and it makes a wonderful noise!
Just comparing the bags between the two bikes, I'd rather have the '02... they seem to hold more, and the mounting looks a little friendlier.
However, being the owner of an '06 for some time now, I'd never think of trading for the older version.
If I were in your position and happy with the '02, I'd walk away from the trade, avoid the under-seat mod, spend a bit of the money on a end-to-end inspection / service and spend the remaining money on a grand road trip; something like East to West coast, home through Canada.
But I'm not normal

and you know what they say about free advice...
Either way you'll have a wonderful bike.
Cheers! :-g
~Randy DTFR
Ride safe!
[ This message was edited by: RandyDTFR on 2007-03-12 21:19 ]