Fixed blade... full tang. Can it get any stronger or faster to deploy? I don't think so...
but... folders are easier to carry. Balisong are less technical to produce in a non-industrial setting (think older Manila) than the high tech locking folders. Thus, they were probably made with carryability/portability (plus lock strength) in mind versus a fixed blade. I think this was the intention versus doing the fancy flips.
I really doubt the many many knife fights in the streets of Manila involve lots of bali-flipping. And those folks are quite the knife fighters. Their fixed blades are probably machetes.
I liken flipping the bali to having an open cylinder on a revolver. You can close it nicely, or you can flip it shut one handed because it looks cool. But doing this isn't really good for the revolver, nor is flipping the bali. Of course a lot of fun time is spent doing tricks, but I see them as just tricks, not fighting techniques.
Clay, Chuck, all those guys from the forum are awesome at flipping, but I really haven't seen much of them related to knife fighting techniques... that Master Po guy on the other hand looks like he knows some stuff though.
but yeah, if portability isn't an issue, a fixed blade is certainly the way to go IMO.