I neglected the bi-amp thing.
Provided both amplifiers are receiving the same signal from the same terminal on the pre-amp, any differences between the final signal would be the result of nothing more than variation in manufacturing. Provided both amps were the same model, no self respecting manufacturer should have dramatic differences between their finished goods. You still aren't bypassing the cross-over. An internal filter still must be employed by the speaker.
Now, if different amps are used with different characteristics for a specific outcome, a difference could be possible. Whether that difference was "better" would be another issue entirely.
