Thanks.

I did comparisons at a range of apertures and as you'd expect both lenses improve the more you stop down, however if anything the 17-40 moves closer to the TS-E.

I'd probably be happy with the TS-E as it was if it weren't for every review, especially the one on this site telling me how amazing the TS-E is wide open (which is what I'll be shooting at much of the time) and how it even edges out the dedicated 1.4 24mm L.

I've already returned the lens for another one.