I am also a fan of Josef Siebel's shoes - I almost always travel with a pair. The only exception is when I travel to winter climates, in which case I take a pair of comfortable shoes or ankle boots with a sufficiently grippy tread that I can walk on snow and ice. I looked into having my shoemaker add such a sole to my Josef Siebel's but he said it couldn't be done properly. Winter climates would include any environment where there is a risk of the temperature dropping to zero (even if there's no snow, you sometimes get patches of black ice) - and that would include a lot of Europe right now - through early March at least.

I agree with other posters who said you should have two pairs of shoes. On several trips, I've ruined one pair of shoes (e.g. in a downpour) and I would have hated to go shoe-shopping for something comfortable on an "emergency" basis.

Also, if you buy a new pair of shoes (especially if you only take one pair with you), make sure that you test them over a full day (including lots of walking and standing) - to ensure that they don't cause blisters or other discomfort. Regardless of whether or not a shoe is designed to be a comfortable walking shoe, some shoes just don't fit certain feet. You don't want to ruin your trip with uncomfortable shoes.