Personally I’d never run a pedal like the H9 in a loop unless I wanted to run it in mono. With the latest firmware the ES-8 can do separate effects on the L&R so you can run different pedal paths to L&R as well as sharing some, so if you want to say, use the H9 on a patch only the R or L, it makes sense to put it on a loop. I connect my H9 to the outputs of my es-8 and when I dont want it on I send the PC for bypass. I guess the only downside is it always has to be last in the ‘loop structure’ but so far that’s made more sense for what I’m using it for (heavy on delays and reverbs).
