newer beacons are faster, less prone to spiking, and a bit more user friendly.
IF you practice with a T1, you're likely just fine & it's no big deal upgrading, but wouldn't hurt either!
Keep in mind, when you upgrade & then subsequently sell your old beacon... you're likely supplying someone who wouldn't have otherwise bought one possibly, so you're contributing to the greater good! (yeah, that's how I justified my S1 anyhow!!!)
my Buddies and i all got together today to do some practicing with our beacons, and the tracker 2 seemed to be the stand out in the bunch. the readouts are real easy to follow while running toward the buried other beacons. it was able to find two beacons burried 100 meters from our start point in under 3 mins. it was impressive, some of the f1 focus' took 4 to 5 mins so now im on the look out for a new one. jme
I think it all depends on how comfortable you are with your current beacon and also if you are willing to shell out the $$$ for a new one or not.
If you are comfortable with the current one and know how to use it well, no there really isn't a large reason to get a new one. If you have used your current one and are not happy with it and you have the money to get a new one, then by all means up date to a new beacon. Good luck and safe sledding.