I use triggers mainly for playing metal and fast double bass. I use them combined with Roland TM-1 module connected with two separate inputs.
Pros:
* Triggers don't depend on the vibrations of the drum head, so a lot of false triggering coming from sympathetic vibrations caused by other drums and instruments is eliminated.
* In essence triggers need to be set/mounted only once. Once set/mounted, you only need to adjust them accordingly by bending the metal, on which the sensor is mounted, when moving the bass drum pedal from bass drum to some other drum kit/bass drum.
* No need to change trigger settings in the module to accommodate different bass drums, or need to meddle with the bass drum to avoid false triggering.
* Extra replacement sensor that is easy to replace.
* Ability to buy more replacement sensors from the manufacturer, which are pretty cheap in my opinion.
Cons:
From subjective point of view I couldn't find any cons, but I can see that some people might consider the following things as a con:
* Need to buy extra cables to connect triggers to a drum module
* To avoid any problems you need to use two inputs on the module instead of one.
* The sensor is being hit directly, so it can be easily damaged if not set properly (Is mentioned by the manufacturer).
All in all a very good affordable product for drummers that play a lot of fast double bass.