Brief aside: Although I primarily play bass, as far as gigging out goes, I've been playing guitar just as long, and if a pedal can't serve with both bass AND guitar rigs, then it's outta here. No problems on that quarter with the ModFactor. I'll address sound quality first, because that's pretty much the only place I could find fault with the unit. While it's sounds are very, very good, I AB'd them against a couple analog units, and you can tell there is a difference in tone and timbre. Not glaringly, obviously bad, by any means, but the analog units (Morley PFL flanger, Moog Ring Mod, and EBS envelope filter) were definitely a little more rich and full. In a live environment, I doubt anyone would notice or care. That said, there are certain things that just can't be done on an analog unit, and that's where the Eventide shines. For example, with the ModFactor, you can modulate your modulation... basically, you can modify the waveshape of the up-down swoosh of a phaser (or flange, or ring mod, or...) by an independent "invisible" up-down swoosh. So you can get some really nifty drunken stagger waveshapes going on. You can control any parameter via expression pedal, and there are a ton of different waveforms to choose for the modulation and the modulation of the modulation. Sine, Triangle, Ramp, Peak, Random, Sample and Hold, ADSR, Envelope... You can control any and all parameters with an expression pedal. This is damn-near crucial for me. Nearly half of my gigging pedals have some kind of foot interactivity, beyond bypass... I treat my pedalboard almost like another instrument, or like a logical extension of my bass. I try and cop a lot of synth tones, and to me that equals interactivity. There are so many sounds in this thing, and the different ways you can modulate them turn them into other effects. For example, you can set the lowpass filter to expression pedal control for a wah effect, or sync it to a tap tempo and change the wave form for a sample and hold filter. You can map the sweep of a flanger or phaser to the expression pedal for weird resonant sweeps. Speed up and slow down tremolo rates. Random pitch vibrato. It goes on and on... Presets.... I love anything with presets. I love being able to tweak, but it's fun to NOT have to tweak, too. Especially with a pedal this complex; I've already lost three really awesome settings because I forgot to save them, and there are just so many parameters to tweak it's easy to forget what the hell you just did. They're pretty easy to get to, and although some functions are lost when in preset mode, you can call up a preset and switch back to manual mode to gain those features back. It takes a few seconds, unless you have the add-on footswitch. The add-on allows you to map a set of functions, bank up or down, tap tempo, brake, half-speed, etc., and seems a pretty crucial piece of gear if you plan on using this thing to the fullest of it's abilities. I'll pick one up eventually, I'm sure. Mine didn't come with a manual, so I downloaded the .pdf file, and honestly, it's pretty anemic. It explains how to navigate all the features of the pedal, as far as calling up presets, accessing various modes, etc., but doesn't tell you squat about the sound models themselves. I'm still trying to wrap my head around the Undulator, (dual delay lines, chorus, and a trem, but that's ALL the manual tells you!) IThe Undulator mode is capable of some amazing sounds, but I don't know HOW it's making them. Programming the effect is pretty much like shooting blindfolded. I've gotten some beautiful string pad sounds, a faux MAX/MSP effect , and a weird, almost backwards delay Slow Gear kinda thing... Anyway, in summation; LOTS of great sounds, versatile is it's middle name, very interactive, and presets to save your hard work. No noise; in fact, my tone seems a little clearer with the ModFactor in line. Tap tempo! It's already made it's way onto my live board. CONS: * Not quite as full and lush as analog effects, but I wasn't really expecting it to be. I can live with the tradeoff, as the difference is fairly subtle. *THE MANUAL. You'd think that Eventide, a company renowned for it's rack units, would put forth the effort to make a more comprehensive manual. There are a lot of different sound models, and some of them would benefit greatly from a little extra explanation. * Perhaps TOO complex for those of you into the plug-and-play aspect of pedals. This one requires some alone time to get acquainted with. Any specific questions, feel free to ask.