Long story short - I built a nice 5F4 Super. Next "project" was the 6G15 Reverb ... but before I jumped in, I wanted to see how reverb sounded with the 5F4. I was afraid that putting reverb at the front end of the amp would sound weird when overdriven. And that's why I got the EHX Holy Grail Neo. I've used the original Holy Grail before... and the Holier Grail... which I thought were interesting sounding, not the real McCoy. So, here's what the HG Neo brought to mind. Like the current Holy Grail "Nano" very simple. One knob. One 3-position switch. Settings are: Spring, Hall, Plate. Sounds good so far. The other good thing is usable tones are achievable with these settings, but I think most players will have to work at it a bit. I had to work at it at least! Here's the issue. Maybe I'm wrong, but I think that most players prefer that "little touch of reverb" just to add some sonic depth and dimension to their overall playing - especially in a small enclosed space - aka your home practice area, or a small venue if you're playing out. The biggest indoor place I've ever played was a high school cafeteria/auditorium. No need for any reverb there! With the HG Neo, all the "subtle" reverb effect is stacked into about 1/16 revolution of the dial. You have to be really... really... careful with the adjustment to add just enough reverb to give your playing some depth and ambiance. The dial will quickly turn into heavy surf, then over the top reverberation. The last 3/4 of the dials rotation are pretty much reserved for "weird" category. I suppose there are uses, but limited I'm sure. As for the tones you get when the HG Neo is dialed into that little sweet spot, they're not terrible. There is a very subtle difference between Spring and Plate. Depending on the dial setting, you're seeing variation in the attack of the effect, and the tonality, with the plate having a slightly softer attack and overall "fuller" tone. The Spring setting has more snap, more high end, and can be very surfy toned. The Hall setting is a different. There are hints of remnant Flerb in the tone. In other words, the "hall" in the Hall setting is ginormous! Big as in "just short of the Grand Canyon" in size. It sounds like multiple overlapping echos from distant vaulted ceilings and far off walls. It has an almost tunnel like tone. And therein is the issue. Those "repeats" are completely regular in their time base, no matter how its set. A sort of "slap slap slap...." effect. I don't care for it much, compared to other simulated hall settings. I'm sure it has its uses though. Its hard to describe how the dial works. Its not like you're hitting a plate or tank harder when you increase the dial's setting. Its not like a wet/dry mix control either. Its more like increments of each, that quickly go out into space someplace. I tried splitting the reverb off into the other channel of the 5F4 and using that as a "mix". That worked ok, but I've gone back to using the pedal without splitting off, and just being really careful with the dial's setting. Bottom line - do I like it? Yah its ok. Its not great. I didn't expect it to be great. I bought it as a test to see how the overdriven 5F4 would sound with reverb. It sounds great! So the 6G15 Reverb is on order! Am I down on the tones? No, it has three distinct settings of tone flavor, and I find the spring and plate are not bad at all. The dial is a bit edgy. I realize that one pedal must cater to the subtle crowd (aka me) and the "over the top" crowd too. Would have been nice to put more of the subtle effect into a bit wider section of the dial. Dunno if that's pot taper or digital programming in the pedals brain at fault. I'll probably gift this pedal to someone, once I've got the 6G15 all assembled (six week wait for cabinet to my spec from Mojotone). And thats about it.