Davie just been looking at your Scotland by Lay By.
1. "Auchmithie nr Arbroath" "product of 13 separate photographs edited to make one superwide view."
Yep 8-16 or 10-22
2. How many of your images are hand held i wonder
Sigma 8-16 : f5.6 HSM handheld in early morning, dusk, Scottish weather ?
(although Beth's images seem to suggest f5.6 may be ok)
Canon 10-22 : f3.5 USM wouldn't that be easier handheld.
3. Corner to corner sharpness : i dont think needed for sweeping landscapes
(forego 14mm prime)
ultrawide zoom more handy for your images.
Distortion easily correctable in sw.
(& finally if you have £1.8k to burn either of the uw zooms & sigma dp2m [stalkeyes])