Speaker Asylum: Question re. delay in an active XO by andyr

AIUI - please tell me if my understanding is skewed - there is always delay involved in a conventional IIR XO:
* 6dB slopes result in the 'lower' driver being delayed 90 deg, compared to the 'upper' driver.
* 12dB slopes produce a 180 deg delay - so one of the drivers is generally connected in reverse polarity, to compensate for this
* 18dB slopes produce a 270 deg delay and
* 24dB slopes produce a 360 deg delay - ie. a whole cycle ... so the drivers can be connected with the same polarity.

But what if we use an active digital XO - like say, a miniDSP 10x10HD - to provide the filters?

This offers delay - my question is ... should this delay be used, to deliver a better result?

For instance, let's take a 24dB XO between mids & tweeter @ 3kHz:
* for simplicity, let's assume the speed of sound is 1000fps
* wavelength at 3000Hz is 1000/3300 = 0.33ft
* so the mid driver is delayed 0.33ms behind the tweeter.

Should we therefore set the delay on the tweeter in the 10x10HD plug-in to be 0.33ms, in order to time-align the tweeters with the mids?

Andy