I installed a shockstop stem on an ST1 yesterday. It mounts identically as the original stem. The spacing for the 4 screws that hold the face clamp were a different spacing than the original. Simply swapping the stem is a no-brainer. If the light mounts on the handlebar, and the clamp goes either side of the stem, then the stems bar clamp assembly width is a concern. The ShockStop's bar clamp assembly is 1 and 3/4" wide. If the light is integrated into the front plate of the clamp, its likely a no-go. I cant tell from photos how the light mounts on the ST2.
My first impression was the recommended elastomers for my weight for a flat bar were way too stiff. I dropped it to the next level down, and there is still very little flex. I'm going to need to ride it more to see if there is any benefit. Right now, I'd say it doesnt seem to do anything for me, but I've only ridden smooth pavement so far. I can go way down in elastomer choices yet. Lots of selection. I noticed after installing it on the fork tube, there is about 1/4" of clamp above the fork tube. IE the fork doesnt fit flush with the top of the clamp. I put the original back on and its the same. I could have removed a spacer ring, but seeing as how the original stem has the same gap from the factory, I left the shockstop with the same recessed gap. Tried 4 times to wiggle/press/whatever I had to do to eliminate slop in the headset bearings, re-clamping the stem clamp bolts till I got it right. Using the ShockStop in the slightly inclined orientation to get a bit more height/upright position.
The ShockStop is rigidly connected to the fork tube and handlebar. Its pivot bolt is firmly securing the two parts. No slop in the stem. The elastomers only allow vertical movement, and with the elastomer I have in now, that movement is pretty minimal, if any. You will have to ride with weight on the bars to feel any suspension effect. The bar doesn't "float" in elastomer, so you will get vibrations from the forks through the bars - as the pivot is a secure mechanical link. If you have weight on the handlebar, you will feel it give hitting a bump, and absorb shock. Its effect will depend on where/how you ride, and whether you have weight on the bars. Only a guess, but their chart for flat bars is likely with mountain biking in mind, and subsequently riders will have lots of weight on the bar in various modes during riding. For commuting with a more upright position, I feel I can go a lot lighter than their suggested elstomer setting.