Another long-term Allez rider here. Bought mine back in 2009 as my one-and-only-everything bike. It as taken me on all my 100 mile rides (10, now), through the snow and ice (a bit crazy, that one), floods (this year), over hard knott and wrynose, and through rain and shine. I've had a wet weather bike for a number of years now, so it has been relegated to fun rides (Audax, sportive, long social and commuting in the dry). I've upgraded the 2300 groupset to 105, and is now much better, but the saddle, frame and handlebars remain unchanged.
I would replace it but:
a) can't bear to part with it as we have been through too much pain and joy together to part.
b) can't justify an upgrade.