Chris: bluetooth is much more convenient, yes. But the bandwidth and stability is actually significantly higher on wifi (typically 54-2000 mbs vs 3 mbs for bluetooth, hence why there's no latency with streaming audio through wifi but there is with bluetooth).
But for me the biggest inconvenience of UDWL01 is if you're using internet direct connection, you can't use your home wifi at the same time* whereas bluetooth conveniently lets you use your existing wifi network on your smart device. Also, vs using a wifi direct connection, bluetooth won't disconnect from your smart device just because you've switched apps.
*Yes, it's supposed to work if you connect both the piano and the the ipad to the same network. In theory. I Haven't been able to get it to work (probably due to wifi exceeding 2.4 GHz)
However, if I recall, while the UDWL01 will work with the CVP609, I didn't think the smart pianist app did (they may have updated Smartpianist since then, though. We tried just as the 709 was being rolled out, and at the time, no). The CVP701 also didn't work that way.
Mark