Doesn't sound like you have a great case. You might have a better case in 2 months when you need a feature of PCRE that isn't available in Boost. :) Only suggestion I would make (if you think it's the right thing to do) is to propose an thin abstraction layer over Boost/PCRE that would allow you to switch between Boost and PCRE where needed.

Every feature impedes performance.

Considered by osunderdog: "Slightly OT. Move to Meditations".
Unconsidered by davido: This followup would be out of context if it got moved to Meditations without the rest of the thread. Final vote (keep/edit/delete): 5/1/0.