I tried this connection scheme.
One additional advantage of using a DL32 on each port of the M32 (with firmware V3.11 or 3.12 anyway) is being able to directly use aux remap aes50A or B 1-6 without having to burn 2 mic pre's on one DL. You will get preamp gain control on those aux remap ch's BTW and you should get it using the other routing methods too. The obvious drawback is that second long cable from FOH, however at least you already have one as you used it with your loop routing scenario in the original post.
The User input and User output menus in V4 are very powerful features and are imo worth the few bugs reported. The extra routing potential is immense. Rumor has it firmware 4.01 is soon upon us anyway.