One of the problems is to KNOW just what kid of load you are driving?
Resistive is relatively easy, bit with these CFL's type things, nearly nothing is resistive anymore. It's also ESPECIALLY important when doing phase angle firing.
You could turn on at one voltage zero crossing and suddenly a current zero crossing shows up and you load is turned off. Oops!! For reliability, your best to trigger, burst wise, for an entire period or at least close to one.
Watch the quadrants that the triacs trigger in and the different thresholds.
For higher reliability, back to back SCR's are recommended. I know there is a case where, they should be fired together, but I forget why. I THINK it's a surge thing. Higher reliability might also result in using a triac trigger transformer rather than opto-isolated.