Depends on how you are going to get your tune..
The 4-position flip chip can hold up to 4 tunes + PCM Bypass.. You can change them VERY quickly (Car off, Turn the knob, car on).. You can also reset back to stock PCM by setting it on Selection 4 (5-8 are deadman selections.. No-Start conditions, 0-3 are Tunes)..
You cannot datalog with the chip. Depending on your car, you can't use the chip.. If you have the knowledge and cash, the PRP package and the chip burner allows you total control, with speed.. But, no datalogging.. The chip will also allow you to span a wide range of PCM codes and doesn't VIN lock.. Meaning, you can find a local tuner that already has a compatible PCM code and won't have to fork out the cash for the extra Strat code if you get buddy buddy with the tuner..;
The flasher is slower, very very slow compared to the chip.. Its VIN locked, but you can datalog (or are supposed to be able too.. grumble grumble svtf grumble sct grumble) and it'll work with the newer PCM's.. Plus, you'll be able to pull FORD ODB-II codes (its not universal) and clear your CEL's..
So.. if your going to be doing multiple tunes (like a 93, 93 + nO2, valet mode) and need to be able to switch between them quickly, the chip is yer best bet.. Especially if you're going to be tune it yourself..
2003 SVTF - Stage 2 Eibach Sportlines, 75mm UDP/38MM ODP, 28.6MM RSB, CFM STS - Tuned by Tom
2006 MazdaSpeed 6 - Zoom zOOm
1998 Escort ZX2 - Currently in Pieces...