Probably not
WiFi speeds are generally poor on WM devices- neither of my devices can connect at more than about 900kbps according to the speed test program I use. My 3 HSDPA connection manages the same with a good signal.
What is interesting is that even with a good signal, web page loading on the WM devices is much slower than on my Advent Netbook with built-in SIM slot. Even full PC style pages load faster on the Advent than mobile optimised sites on the Diamond or Ameo.
So, the poor speed over WiFi may just be a symptom of poor overall speed capability in mobile devices.