I then have another controller/laptop plugged into input 2 on the back of my tops with input select to A + B so I can jump immediatley to an alternate system if my laptop locks up and/or I have a primary controller failure precluding to going to a secondary input on my primary controller. Works pretty slick...
Why do you go to the tops first? That requires 2 XLRs going up the pole. I would stick with the dbx to the sub and then your choice of outputs to the top (since you can either set the 100Hz low cut on the top or use the 100Hz low cut output on the sub).
This photo is actually linked to another thread which explains (regarding my new dbx GoRack). The reason I go to the tops first is the subs completely kill the tops if they ever fail. Had that happen with my single B15ooD Pro sub running to two tops which operates in the exact same configuration as the B1200D Pros. If you lose power or it goes into protection it completely kills the signals to the tops meaning dead silence (Powered pass through circuit vs a passive one I believe). Now that I run 2 subs vice one (usually) I know the chances of both failing are quite small. However, I would rather lose just the sub rather than the tops and subs (since I can switch it quickly to full range from High pass) if either one ever failed. The Hosa unit seems a good idea but I don't like to mix and match TRS with XLR - to many cable conversions and adapters etc. I try to go XLR wherever possible because they are easier to extend...
I don't really mind the extra cables going up the poles - I actually have a third line going up as well when you factor in my redundant system feeding input 2 at the back of the tops - saved my bacon more than once...