Ross, I'm surprised you've experienced such high levels of latency... I think, though, that Bias has more latency than JamUp. Certainly, when I play, there's no detectable latency in JamUp, and I know from experience with my former laptop setup that 15 ms is easily felt and above 20 ms is completely unplayable, so my iPad minis must be below 15. And that's on both the newer 'retina' model and the first-gen model which is supposedly about the same processing power as the iPad 2.
It's a shame because, if nothing else, using the iPad/iPhone/iPod is convenient for its size & portability.