The products are similar in their intent, but different in their mechanisms and the degree to which they work. To break it down simply:
StimX
-8hr formula
-Mild to moderate appetite suppression
-Clean energy, more feel, more towards the "jittery" end for some, little to no crash
SX
-12-14hr formula
-Heavy appetite suppression
-Clean energy, mild "mental" energy, not jittery, no crash at all
Each of them has their merits and which is better for your goals depends a lot on you and those goals. If you're looking for a stimulant with more of a classic stim feel to it, then StimX would be the one to go with. If you're looking to be more alert throughout the day to get things done, have the motivation to get stuff done, and don't want to worry about feeling hungry or having cravings all day, then SX is the one for you.
Personally, I'm a big eater. I have a desk job M-F, 9-4 and hit the gym afterwards. I'd rather not feel the need to eat while I'm forced to be sedentary throughout the day, but I don't want to get so bored that I fall asleep here. SX is my answer - keeps me alert all day and kicks cravings to the door. If I were going out to a concert and wanted high energy for 7-8 hours or so and wasn't as concerned with not eating, then I'd go with StimX.
And yes, I've stacked the 2 together. Do NOT do that!!!!! :nutkick: