Thanks a lot for your valuable opinions, I really appreciate.
Even BSP has is own drawbacks. You need to clean models from invalid triangles, do pre-processing each time the model changes, decide how many candidates to take to balance the pre-processing time vs. FPS.
After some years I always ask about transparency on this forum and the answer is always "it depends...", transparency has to be the most complex thing on earth to solve completely ;-)
@Dukey: regarding Dual depth peeling why you cannot give the user a level number option an leave him/her to decide how accurate the transparency will be?
Why aren't you doing BSP at triangle level?Pitty most model formats aren't actually BSP trees