For what its worth, Ben, I've got those boots, had 'em for about 15 years (honest!) and I love them...ride down to Yorkshire, get Your feet and bits measured at the shop, they'll last forever (can even get them resoled).
They've taken me all over Europe (well, France, Spain, Germany) Ireland (where they invented rain) and never let a drop in. I've even hiked short ditanced in them, when pushed - or pished, as Hutchie would say!
I've got the opposite to you - skinny calves - and there's a bit too much room in them at times, when walking in them, but that was my fault for not saying at the time of fitting, and it doesn't bother me...
However, these boots look canny to me, £149 and came out well in ABR mag...
http://www.tranam.co.uk/Clothing/W2/W2_4dirt.html