Well, so far so good.
The card is still working and I can read/write to/from it without any problems.

It isn't a perfect fit. I was looking at it, and its a bit thinner (wrong word, it's a bit shorter side to side) and a bit shorter now (top to bottom). The actual thickness is about the same, maybe a tad less, but close with the back on.
As it is, when I slide it into the slot, I'm not sure it "clicks" properly and its in at a slight angle, I think because it's a bit less wide. And its tricky, but not "that" hard to remove it.

I'll look at possibly adding a bit more plastic to get it to be the same size as an old MMC.

But, for $10 and 5 minutes to get 4G... Not too shabby. :-)
I suppose, now that I know that the card is half height, I could start with another card and just cut the top off to the correct height and then dremmel it down to fit, rather than taking it all apart and trying to put it back together. :-)

desiv