FWIW, I mainly use the front panel. I have a default session saved with a few algorithms pre-positioned and when I want to try new things, I call that session up, arrow over to one of the FX chains, and replace the algorithm.
I’m usually in 2 different mindsets – I either want something specific (I need a panner or simple delay) or I’m doing sound design and auditioning algorithms semi-randomly. What helps a lot is that I have a printout of the algorithms from the H8000 preset manual and simply call them up by number directly. I’m rarely scrolling through more than 1 or 2 spots and that’s mainly because what I want to audition is adjacent to the current one. Even though it doesn’t cover the newer ones added from other units, it has the bulk of what I care about (until Eventide gets around to publishing an H9000 preset guide whenever they finish getting the algorithms all ported).