I would forego the back-up since it has to be a 4" barrel. You stated that a Taurus 1911 is your primary weapon. The 1911 is a platform that "even Taurus" can't screw up (except for a few proprietary parts). Regardless, you don't sound like you absolutely love it. My suggestion would be to take the money (you planned to use on a BUG) and add it to the Taurus 1911 for trade-in on another gun (like a nicer 1911) you actually would prefer to own.
Sic Semper Tyrannis