I alternate...the biggest difference between singletap and alternate is the fact that alternating needs more control for a high accuracy, but you won't have to practice singletap speed for high BPMs because...well, you just alternate.
My experience regarding alternate playstyle:
Pro
+not as limited by BPM of maps (more maps to play)
+more stamina
+both fingers get equal amount of practice
+less strain (!)
+more fun =P
Con
-requires more control for high accuracy, even if it's just 1/2s (OD10 at least)
-long time to get comfortable at it
-harder to stay on beat on streams (really subjective)
When one finger is dominant, it can act as a metronome for the other, thus making a stream just 1/2 with notes in between for the other finger to tap. I'd recommend just sticking to one and switching when you are not happy with your results...you won't be limited by your playstyle in that regard, don't fret. Experimentation can only help you improve.