Thanks for the terrific review! I have to agree with dtrain that you may have been better off with the 54. Having said that, you can try a longer stem and see if that works for you as rms pointed out.

I would invest some money working with a fitter to max out your comfort and efficiency.

At the very worst, you can sell the bike and size up one if that's what works best.

That was my main concern with BD; not being able to test ride.