Hi Jim,
Like you I do have some spare time ... and I hope you guys are safe over there in NZ; NZ like us in OZ seems to be doing a great job so far 
... anyway...
I have used standard IIR filters for the above .... but I have also used LIM crossovers with all-pass filters for a flat phase and amplitude response. I have not needed to use the FIR modules yet. I can post these settings if people would like (?)
The latency of the LIM crossover is 1.19 / crossover frequency in KHz ..i.e. 100 Hz = 11.9ms + plus processing time for the AD/DA. There can also be some latency associated with the Vx limiter (Virtual Crossover) if you use it (max 1.53ms or 0.12 / passive crossover frequency in KHz)
Most shows that I do have at least 5m (16.4 feet) from the drum kit to the FOH ... or about 15.5ms to time align the FOH to the back line, so it all works fine. The problem with the Lake is that you can have 2.5ms, 5ms, 10ms or 20ms FIR time (in 3 way stereo mode) 20ms is often too long and 10ms only allows a LF crossover down to 125Hz if you want to use a 24dB LR curve.
If you use all LIM crossovers and you find you need less latency for a show just change the LF crossover to 24dBLR and it will automatically correct and reduce the latency to suit the mid frequency LIM crossover point.
I have not used a HPF for the subs but instead I have used excursion limiting that is available in the ASC48. I have also used this on the LF section of the PM60 (in addition to a 100Hz HPF)
