There is a difference between LE vs civilian model Tasers (read below). As far as effectiveness... VERY EFFECTIVE as long as the probes both puncture skin a decent distance apart to allow the the charge to effect the nervous system.

The TASER X26C was modeled after the law enforcement TASER X26, and utilizes the same proven technology. One trigger pull of the X26C initiates a 10-second cycle, while the LE model runs for 5 seconds. Moreover, the trigger on the X26C can be pulled several times to create a 30-second cycle. The user can then deploy the X26C, quickly squeeze the trigger 2 additional times to create a 30-second cycle (3 pulls x 10 seconds = 30 seconds), place the X26C on the ground, and depart the scene - while the X26C safely disables the assailant.

The law enforcement version cannot be triggered multiple times to create back-to-back cycles. Cycle times on both models may be interrupted by placing the safey lever in the "safe" position. Per second, the LE X26 delivers 19 pulses of electricity into the target. Since the X26C is capable of delivering a much longer cycle, these pulses range from 19 per second for the first 5 seconds, then drop down to 10 for any remaining time. In addition, civilians may only purchase air cartridges with a 15-foot range, while law enforcement officers have access to cartridges with ranges up to 35'. Finally, the X26 LE model records time and date for each deployment. This feature helps protect law enforcement agencies from claims of excessive use-of-force, and also provides management a powerful tool to track usage patterns and prevent misuse. The firing data on the X26C is not recorded, and cannot be downloaded.