Well supported thread, with good information.
My experience.
SRTs have pretty tall 3:07 gears. They are the strongest, run quiet, and come free with the car.
Stock gears are the best, smoothest and usually fastest on longer road courses. Not so much shifting, and good long dig out of the corners. These long gears are good to take a set on long corners, and you will not find yourself shifting in corners quite as much. For downshifts they do not seem to upset the car as much as the shorter gears.
For street driving the agressiveness and balance of the 3:55, polished and cryo treated seems to be the most popular choice. Easy to skip a gear if you feel you are shifting too much, and 5th and 6th standard gears are much more pleasurable to use. As Jon says, be careful of your source, and make sure you get the good stuff.
This gear makes driving in stop and go traffic much more enjoyable. Always seems to have the right gear available and much less lugging around. Throttle seems to have much more snap, and the car comes alive with this setup.
Reports are that the rear ends tend to go out a little more often after changing gears, especially if you have more than stock hp.
For higher HP cars, the 3:07 once again becomes the rear of choice, unless you really enjoy the Banzai! skittering feeling when you mash the throttle. (I kind of liked this myself)
Biggest deal with the shorter gears is that the car just feels faster. Zips through the gears with zing, and tends to push the tires to their limits, and sometimes beyond.
I've had 2 geared Vipers. Most fun you can have with a stock Viper, but as you add more HP the stock gears become just right.