I think the hardtop is a great option to have and well worth the money. The top has an intergral roll bar and when the top is installed, the roadster is actually stiffer that the coupe. My car is much quieter inside with the top installed, it even kills some of the resonance from the B&B TriFlo's! Body rattles disappear too.
Make sure you get all of the components with the hardtop. There are 2 fairly heavy brackets that attach the top to the body pillar behind the doors. These brackets use a total of 10 Torx bolts (2 with small washers, 8 with larger ones). The windshield frame has 2 encapsulated bolts in place to hold the top to the frame. Look in the hole in the trim near the sunvisor pivot.
The hardtop should have two more bolts inside the locating pins that drop into the existing latches in the decklid. The factory provided a ratchet with a long T40 driver and a 5/16 ratcheting wrench in a pouch for installation. You will need both these tools to do the install. There is also a decklid protector that slides over the decklid and wedges in place.
The hardtops all have defoggers in the glass. There should be wires with connectors at either side of the top. The car has a hot lead in a harness that you can find near the passenger side shoulder belt mounting tower. Just dig under the carpet and you should find it It's orange/white and about 6" long. Unfortunately, the ground wire with connector for the other side is no longer available from GM so if you don't get it off the donor car, you will have to fabricate one. The OEM ground wire is just screwed to the driver side shoulder belt tower. The defogger works off the heated mirror button on the A/C control panel.
Like Scorp said, NHRA will allow you to run up to 11:99 and you should also be able to do open track days with the hardtop in place.