I have the TFR, love it. If I didn't have it, I would buy the COG Grand Tarkin. Even better, contact Tom from COG and have him build you exactly what you want, and it'll still probably work out cheaper than importing a TFR or buying a Duality.
Have to say though, TFR full-gain into the B3K at half-blend half-gain is still one of the most incredible bass dirt sounds I have ever heard. I want to have a little joyful cry every time I play through them! ...