I've had a pleasure to play titanium handled balisong with 5" blade. It rotates open/ close just as easy as ordinary 4 incher, and easier to catch the handle with more length. So I guess 4" bali with titanium handles would be as fast as 3 incher, with longer and easier handles.
Maybe a well-balanced bali weighs more in its blade than its handles. If the handles get heavier, it will be a more difficult one. Instead, if the handles get lighter and/or shorter compared to the blade, it will get much easier. When you start opening it, at first the "other" handle will fall by the gravity followed by the blade. If the handle fall proceeds the blade enough, you can grab the handle to start pull rotate up earlier. If the handle takes the blade longer, it will delay your timing to grab the handle for any action.
Well... #42 must be great. Or I'll help you rid of yours for free.
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\(^o^)/ Mizutani Satoshi \(^o^)/