In theory, corals grow fastest at pH between 8.2 and 8.3. More CO2 should mean both more alkalinity at that pH and more fuel for photosynthesis. As I'm sure everyone with a reef tank knows, theory isn't always correct in practice.
So if you said your pH was 7.8 and you added the scrubber and it went to 8.2, I wouldn't be the least bit surprised, but I also wouldn't be tempted to add one to my tank. If you told me your pH was 8.3 and it went to 8.5, and alkalinity use went up too, I'd be shocked and I'd buy one to play with right away.
I need to recalibrate my pH meter, but my tank has always been on the high side, especially during the day. I target 10dHk for my alkalinity, so my pH should be a little higher than yours, but not much.