Well, here goes...
Blackburns valves suck (no pun intended) because:
1. They actualy take thought to operate
(I mean realy, the last thing I want to be thinking of while doing 40 down the side of some trail is *grab, bite, twist, push AAAAAHHH tree!!! all with one hand on the bars.*)
2. They are impossable to clean. I dont mean dificult, I mean it is simply not possable to take them apart. (except in the case of #5 below)
3. The soft outer liner slips around while your messing with it.
4. Its complicated. So many moving parts, Why? A bite valve has 1 part and never breaks.
5. Its junk. Mine came appart in my hand while trying to remove it trying to clean the tube per blackburns directions. They dont go back together without glue.
6. They hurt my teeth. Hard plastic????
7. Bulky.
Why make something more complicated than it has to be?