UBZ 2/Kiss 3 Flash

Flash can you please explain "Kiss 3 is not very good". (understatement) reasons other than just your personal opinion. One more question would an UBZ 2 count produce the same results as the Kiss 3 count ? Playing conditions would be 6 deck DOA first 2 cards, S17, RSA, Double after split. 1 and 1/2 deck cut off. Betting spread would be from 1-12 chips. Which one would you use? How much of a difference would there be ?