Few, if any, of the urethane glues are flexible when completely dry. You get to find that out when you remove the "leakage" if you forgot to wipe it down during thedrying process.

Given the choice of adhesives in an application that would permit that choice, I would go with the urethane every time. CA's are too fast, epoxies are too time critical. Both leave you a bit uncertain of the adhesive coverage. Urethanes provide more application time and assure better coverage.