Had one of the original 125 lumen E1 Backup led and I lost it. Looking to replace it, not sure if I should get the standard click tail cap or the tactical? Any concerns with reliability on the tactical? Always seemed to me the more complicated they are the more likely they'll have problems

The tactical is far more... tactical.  The original E1B switch, with which I'm very familiar, is really quite terrible for tactical "flash and move" usage because of its erratic behavior when cycling quickly and timing based switching logic between high and low.  The twist for constant, press through for momentary high is overal a much better design for a shooter's flashlight.  I don't see any reason to worry about reliability.