Interesting. I'll have to try that.
I did a search to see if anyone mentioned this before, but if you load speedtest.net in the Wii browser you get a special version especially for the Wii. I just think that's a cool, sort of unmentioned feature.
Cool...must confess I've never tried a speed test from the Wii.
What happens if you load it in the Wii U's browser?