New price would probably be pretty close (no x-over required for the 212). 212 would be a bit larger/heavier, but still very manageable. The 15/6 definitely wins freq response handily: 40Hz-8kHz to 51Hz-3.5kHz. 15/6 wins the Vd, too, 845 to 660. Sensitivity is all 212, though, 103.5 (drivers only). Plus add another 3dB for a 4 ohm cab vs. the 8 ohm 15/6 (unless you got a specially-made 4 ohm 3015LF). Not sure how to calculate the 15/6. The 3015LF reads 99.8 on www.usspeaker.com , but that's incorrect. Is it more like 96? The 6ND410 is 102. The 15/6 be an 8 ohm. Would it be 570 RMS (450 + 120)? Or 450? The 212 would be a 4 ohm & 800 RMS. Maybe comes down to whether or not someone likes/needs the greater frequency response? What do all you cabinet sages think?