I have a mixer with 4 aux's already not including it's normal mix as well.
It has 1/4inch only inputs, but most DI/splitters have j1/4inch parallel, it's more the xlr in and out so that the mix is split undisturbed.
Like I say I have 4 ART active DI boxes that do this already but I have to set them up individually at the gigs and get them to turn phantom on, on the board. A rackmount solution would allow me have all the jack to mixer connections done and not require phantom, each band member would unplug the mic on stage run it to the xlr out on the rack and then run another xlr from that back to the mix, might even get a stagebox for this so it's all centralised.