I dunno if anyone else does this, but for a long time I have two "dirt" pedals in my OBEL, an HM-2 which is balls to the walls distortion that has nice compressed gilmourish lead tone that honks quite nicely with the tone knob turned down, and a SD1 that gives me a OD crunch which I use most often. I place them in my OBEL as an effect I want to bring in and bring out during a song or jam quickly and easily. Then at the same time, I would run a Tube OD at the end of the chain right before my delay that goes to the preamp. That one is barely up to emulate a soft clipping as a part of my overall amp tone, despite any effects I am using at any one moment, its always on. I use this pedal especially when I can't be loud enough to get it out of my tubes/amp due to volume constraints usually.
So depending on what you want to use it for you may want to put it in one or the other places. I kinda think of my OBEL as the set it and forget it area, and my short guitar to amp run the tweaker ally. that is why I keep my delay in that line too.
I don't think you will run that much of a tone difference in either placement, especially if you have a buffer and its in its own loop within the OBEL like a pedal switcher. One difference would be that turning the volume of the guitar up and down wouldn't really affect the pedals tone within the OBEL but would right after the guitar in line with the preamp. Try it out in both, see what you like! As transparent as it sounds I would probably opt for using it like a part of my preamp as a tone shaper/clipper always on.