Paul, I've made some edits on this site to accomodate a workaround for IE10.
If you view that site in IE10, you should get outside arrows on IE10. You should get vertical spines on IE9, IE8, IE7
One thing that's puzzling me is this: On IE9, the developer tools shows spines perfectly aligned in all versions of IE it displays (ie7-9). However, when I upgraded my Win 7 box to IE10, the developer tools view of IE shows spines misaligned on all versions of IE it displays (ie10 down to IE7).
However, as you predicted, the IETestor app shows spines fine in all versions ie7-9