I have had both boats, Tornado's and other boats.

If you are not racing in the hobie circuit, and you have moderate winds, the dart is the best boat in the world. I say this for the following reasons:
1) It is real light and you will be shocked how one persson can handle it on the beach.
2) It has totally linear handling, no surprises with pitchpoles, etc. Stuff it up to the rear cross bar and it will slam on the brakes and pop back up.
3) It is kind of a cross btwn an A cat and a 2 person boat, and works pretty well for both.
4) Ain't nothing on that tramp, no adjustments
5) No boom
6) Quiet!!! No swirly water noises, no humming boards, dead silent.
7) It is 8 feet wide, so trailers a bit less obtrusively.
8) You can sail it in 40 knots of wind, 2 up, and sail past all sort of pitchpoled boats laughing

And the drawbacks:
1) A bit underpowered if you are in a low wind area (actually this is its advantage as the winds pick up)
2) Limited dealers, but everything is mail order these days anyway.
3) Not much of a class

And just a warning, DO NOT confuse this with the Dart 20. It is a hulking lug, and this is one of the boats that I truely hated owning. If you want a 20 of related design, get a tornado or prindle 19.