A question (with no positive answer I'm afraid, but just in case)

Hi fellows

I'm feeling sometimes tempted to sell my 50D and 'crop equipment' and then buy a 5DII (I already have a 1DIII).
But there are a couple of things refraining me of doing so.

One of these points is that I have the EF-S 17-55 f/2.8 IS... and I cannot find a zoom lens that would server to the same purpose in the full frame world.
The closest possibilities, the way I see it, would be:

-> 24-105 f/4 IS. I already have this lens, but compared to the 17-55 is 1 stop slower

-> 16-35 f/2.8. While it is wider than the 17-55, I feel it would serve me well (complimented with the 24-105)... but then the lack of IS could be bad news depending the type of photography (light-limited indoor and no flash, for instance).

My question is, do you know guys which lens could be used with a full frame that has all the features of the EF-S 17-55 and -more or less- this sort of focal-length (taking into account that 17 on crop would be like 27 or so on ff)?

TIA

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