Sorry on the Xpost, but SFX Engineering isn''t even listed on the main anymore. Which one is better - stereo or mono sound fx?

Well,it really depends on if the effect uses stereo to a noticable extent. Use you ears ans see what sounds right.

_____________________________

zero static music

_______________________

Mono. Samples size is halved and you get more control with panoramic placement. Also, monophonic samples are much easier to loop. But, as LJG said use your ears and see what sounds best to you.