Chaps:
FWIW, I have been using SCT's flasher (XCal2 [9400] and the ancient 9100) with their Advantage software for many years and I think it is an excellent product. A 4-position chip is pretty good if you don't plan on changing the tune often because the chip can just sit there (on the PCM) and you can switch between tunes without shutting off the engine. A chip requires you to pull out the PCM and there is a small risk that the chip will get bumped off the connector, usually frying the PCM. I prefer the flasher because it is very convenient since I tweak my tune frequently. Diablo also makes a flasher unit, Sniper makes one, and there's TwEECer but there is a big learning curve with it.
I have been running a SpeedCal for many years, too. As stated, the pre-99's need a speedo gear change or a SpeedCal to correct the speedo/odo.
HTH,
Chris