Your cactus look great. Most cactus aren't the speediest growing plants. I wouldn't worry unless I saw signs of them growing pointy.
On the grow light you linked, I don't see anywhere about how many lumens (or any light measurements). I suspect if you are growing low light tropicals, these lights would suit you but not for the level of light a cactus needs. But, you are adding supplemental light, not supplying all light needs artificially so maybe they would help. I would be wary of any light not listing how many lumens its supplying. The down side to artificial lights are they are very directional - only the plant directly under the light will gain any benefit, anything off to the side will be in the shadows. You may need one light per plant.
