I honestly have not ever seen it described this well. It's as if you have worked for edge/ wrote their tuning, or at least know the guy that did haha. Thanks bill or the one at php who checks this site.Well, if the Juice was actually a programmer, you wouldn't be able to. However, since the power function of the Juice has always been simply an injection pressure fooling device, then by all means, it's "stack-able". You can use it with either a flash programmer or a chip. Will you see any power gains by using it in conjunction with either tuning device? Nope. It will make the accelerator pedal more responsive and add a bit of fuel in the lower RPM ranges but once the high pressure oil pump has reached it's limit, you won't see any gains above what the programmer or chip was capable of in the first place.
Again, the Juice is not a programmer so therefore it doesn't have any "tuning" on it. It's a variable resistor for all intents and purposes. The CS and CTS Juice/Attitude devices include a transmission tuning option to alleviate the effects the older Juice modules had, but the power gains still come from fooling the injection pressure input to the PCM because the Juice module is STILL a Juice. The display (Attitude monitor) does the transmission programming only.
The Juice doesn't contain any "tuning" for the engine. "Stacking" these devices on a 7.3L isn't really "bad" per se, but there is little reason to spend the money on two devices that will only run just as good as aftermarket programming would by itself (Evolution, Superchips Max line of programmers, Hypertech, or any level of tuning for stock injectors that any of the "custom tuners" does, etc.).