I'll admit.... I'm not even sure I know how to ask (phrase) this question.... I say that because it seems to me that to be able to phrase a question intelligently.....one must know part of the answer...
You say the FIR filters are in the crossover. Is that to say that they are invisible to the end user? Meaning, if someone selects a L/R crossover for example, then irrespective of the unit (Electrovoice DX or Xilica unit WITHOUT FIR or Xilica unit WITH FIR) that you look on the dial for L/R and dial in your slope....the FIR architecture is invisible to the end user? (there is no FIR function to 'select' over & above the other, every day parameters.... like, I want a FIR function of 2.52 on the bass bins)
If I could try to use the car analogy.... both the Corvette and Jeep use pistons but, one might use a cast piston and the other might use a forged.... so they both have an item that does the same thing and to a person ignorant of cast/forged they might appear to be the same thing, (a piston is a piston, a crossover is a crossover) they both still have different qualities and benefits relative to each other. (this is a IIR crossover and this is a FIR crossover??)