I've been using the FX8 with the jumper between Out Pre and In Post for about 3 months now and I wish I would have tried it sooner. The music I play relies upon ambient delays and reverbs with trails. The jumper solution has given me the option of creating one preset for use with any amp regardless of an effects loop.
This 'improper' solution has worked well and has simplified the creation and organizing of presets for me. If a user wants to use a volume block then by all means, set all effects to PRE and place the volume block where it's needed. It is absolutely an option but is not the only way to use the FX8.
This idea that there's only certain ways to use or setup the FX8 and telling people that they are using it wrong if they use any other method is a large part of why I've decided to quit the forum. I'm sticking around this thread hoping to help the OP understand the FX8 is a tool and they should feel free to set it up however they want. There is an understanding of how the signal flows that they will need and I believe that's been explained.
i used the term "improper" very loosely there, and just meant that it was not designed to be used that way.
but in the first moments i received the FX8, i put a jumper cable mostly for convenience so i could hear all the presets going straight to a cab block sim pedal then straight to a FRFR speaker. i believe i was the first person to publicize using the FX8 that way, and have ONLY used it that way on my gigs. for Beta Testing i've used it that way too, in addition to 4cm, Pre only, Post only, etc.
i would still teach the FX8 saying that a jumper cable is the "improper way" to do it. changing the blocks to Pre or Post is the technically correct way to do it, mostly because the OUPUTS of Pre vs POST are intended for different things - instrument input on the amp vs FX return or other line level input.
but this is music and gear, so whatever works, works.
there ARE technical reasons for why something can be considered improper, or not the best way to do it. it's a shame to quit the forum because of explanations that are factually correct. that said, if someone is badgering or condemning another for doing something a certain way, i can understand.
but for all intents and purposes, as far as my understanding of the FX8 goes, a jumper cable is still technically "improper" and changing the blocks internally to Pre or Post to fit your specific setup is the absolute best thing to do.