In reply to billy.grant:
I'll add my 2p worth....
On the Spantiks, I was advised that you need a size bigger than your normal size, and this would seem spot on.
I did have a pair of Baturas in my normal size, this was a snug fit, my Spantiks (which replaced them) are a full size larger than my normal boot size and they are fairly snug in fit. No way would I fit into Spantiks in my normal size.
The UK distributer doesn't seem to bring the Spantik into the UK in half sizes, but La Sportiva say they are available in half sizes on their website. A possible consideration if you were buying overseas or by mail order.
The biggest minus point I can see over the Omegas you mention as an alternative, is the price - Spantiks are around £200 more than the Omegas, that's quite a hefty price tag(!)
Oh, and the inner boots are identical to those used in the Olympus Mons