I run the Edge drag comp with hot unlock and a smarty. I also have guages to monitor the heat and such. Though I am thinking of getting rid of my drag comp and going with a tst comp box. Depends on what you want to do with your truck. Mine is an oversized hotrod rolling on 38's. I have had no real issues with my comp I just want more as I am stepping up the rest of the parts soon.
As far as the differences between the comp and juice, I think the hot unlock is the same. The nice features of the juice are the safety's and guages. Comp is just the box.
Stacking wise, the smarty seems to tbe the one to go with when stacking. It is a nice piece. Adjust for tire size read trouble codes and clear them.
If your going for all out power check out this thread.
Drag comp vs. Adrenaline vs. Redline box...same dyno, same truck, same day! - Competition Diesel.Com - Bringing The BEST Together