I've had multiple Bloops but always found the 1k clean LPF to be too high. The FFXL goes to 330 Hz and sounds so much better with dirt. I want definition and clarity in my dirt and my clean less defined. I always found clank and fret noise to come through with the Bloop. This does not happen with the FFXL and it makes EVERY dirt pedal sound better. I currently have 9 dirt pedals running through the FFXL and I get a consistent, killer sound across my pedalboard.
I set the HPF going into my dirt a little higher than 20 hz so they don't see too much low end. I let the low end on the clean side shine in that regard. I also do this because I run two octavers before my dirt and it sounds so damn good!
I set the LPF on the effected side to take away the brash, harsh upper frequencies. You can set this to taste but that's where mine landed.