Well, now I know where the Series 5 box went after the Series 7B box was instated at the Experience.  It got sent to New York City at the Doctor Who Tumblr Headquarters.  Here is it with the creator of the Doctor Puppet YouTube series with Doctors 11 & 12!


And here's the box when it was in the experience.  If you look at the top of the cornerpost on the right and wood at the top of the doors, you'll see the wood grain pattern is the same.

Bill "the Doctor" Rudloff

There's a Doctor Who Tumblr Headquarters? As in, an actual building somewhere? Umm, ok... 

Was this only ever in the DWE or was it one of the hero props? It's hard to keep track sometimes.

I believe it was the "location" hero prop that got whisked away literally the day they finished filming with it! I don't know if it was used in "A Christmas Carol", and maybe even some of series 6, but given the time the Experience opened I'd guess it was.
Great news to hear where it's gone! It was indeed certainly a mystery, I even came up with my little theory that they'd torn it to shreds to integrate into Capaldi's prop, so its nice to know it's still in good shape. I miss the automotive paint used on this earlier build, it is a bit distracting, and in many ways the emulsion they use now is nicer, but the effect this paint had on it really was beautiful!

I think the Experience opened before Series 6 filmed or early on in the filming.  But this is the same prop that was photographed when they did filming for Time of Angels.
Bill "the Doctor" Rudloff

Well it opened in Feb 2011, and series 6 debuted 2 months after. Not sure where I heard it was whisked away last minute, I think it was actually on here (Timerotor said it maybe?), but if it was, that must mean they had it for some of series 6 at least, given that normally filming starts a good 6-9 months before airing.

Sorry, I should have specified before the London version of the Experience was opened.  Remember when Timerotor/Mark was picking up the TYJ MK2 from the Upper Boat Studios?  He encountered the "a-hole" who had the lamp in his hand for the "new" prop they were building.  And Mark took photographs of the new box, which was having the St John's badge painted on the correct door after being painted on the wrong door.  That was the Series 6 box.
Bill "the Doctor" Rudloff

That was where I heard it! But this is my confusion, it was indeed the Experience at Olympia that opened that February, the filming mystery stands  .
Even more interestingly, here's a promo shot from the early filming of Series 6 (sorry, posting this from an iPad which as we have learned doesn't agree with the forum).



Check out the top left corner on the left door - the wood grain matches identically (one this that can be said for this build, the wood grain is useful!. So this is the series 5 prop as shown above.
I don't know whether a prop was taken to Utah, I don't recall a scene with it, and the diner scene was filmed at Eddy's in Cardiff with TARDIS door mockups just visible behind the door to the back and toilets. Even if they didn't though, the pictures might show that as late as the filming of this, the box was still in use, even if in this instance it's only for promotional material. 

That's a "stock" Series 5 TARDIS photoshopped onto the photo of Karen.  They didn't bring the prop to Utah at all.  And the lighting of it is all weird and doesn't match Karen's.
Bill "the Doctor" Rudloff