Bi-amping is almost always better than bridging for several reasons.
1) If you bridge into mono you typically do not double current output, but the rated watts RMS may double. This ought to give you an indication of how relatively meaningless watts RMS is to begin with, but the real point here is that you will not be using amplifier power as efficiently as if you bi-amp in which case you will be doubling your current output.
2) Related to the above, but also important in and of itself is the fact that many speakers have demanding impedance loads, often times in the bass frequencies. If you bi-amp, you are providing two isolated amplifiers, one to the bass, and one to the highs. When the bass drops impedance and pulls large amounts of current from the amplifier, the amp hooked up to the highs does not see this load and is unaffected. The result is that whereas if you had been running one bridged amp you might have been running out of current and shutting down the highs and mids when the bass kicked in, now you are preserving highs and mids regardless of what the bass is doing.
For these two reasons, especially on speakers which present a difficult load, I always recommend bi-amping.
1) If you bridge into mono you typically do not double current output, but the rated watts RMS may double. This ought to give you an indication of how relatively meaningless watts RMS is to begin with, but the real point here is that you will not be using amplifier power as efficiently as if you bi-amp in which case you will be doubling your current output.
2) Related to the above, but also important in and of itself is the fact that many speakers have demanding impedance loads, often times in the bass frequencies. If you bi-amp, you are providing two isolated amplifiers, one to the bass, and one to the highs. When the bass drops impedance and pulls large amounts of current from the amplifier, the amp hooked up to the highs does not see this load and is unaffected. The result is that whereas if you had been running one bridged amp you might have been running out of current and shutting down the highs and mids when the bass kicked in, now you are preserving highs and mids regardless of what the bass is doing.
For these two reasons, especially on speakers which present a difficult load, I always recommend bi-amping.