I've always been an ISP guy, especially dual gating. But, when I bought my first Randall Satan, the ZUUL+ came out. For almost $300, I figured it had to be awesome, plus they added the Key Thru. Then I got it. I tested it with my SATAN and my EVH Stealth (100S..on the Red channel). No matter how I dialed it in, it would either chop off my notes, or "squeak" every time I stopped. After a few days, I gave up. I can see it being useful for styles like Djent or THALL, but my style is like a mix of Decapitated, Alluvial, UABB, Suicide Silence, etc. So, I quickly sold it and also complained to someone at Fortin.. who then talked me into trying the original Zuul. When it showed up, I noticed he gave me a 2nd one for free! Anyway, other than not having a Key Thru, the Zuul was much better, at least with the SATAN. So, just be cautious. If you like choppy, stacatto type stuff in Drop F, you'll like this. For me, I now have 2 Satan heads with the Zuul PCB's modded into them, but I'll stick with ISP with my Stealths.