I've recently completed builds of 2 WM-clones primarily for the experience of doing it and I thought I'd share some initial thoughts on each one. Sadly, I don't have a way to record at home right now so I can't provide sound samples at the moment.
Build #1
pic here was based off of the Fuzzy Elephant layout floating around. I built this one up on veroboard using parts from Smallbear (with the exception of a couple of caps I ended up getting from RadioShack). I made a huge series of rookie mistakes with this build - 24mm pots instead of 16mm, not laying everything out properly drilling, botching the paint and decal jobs horribly, terrible wire-routing, etc. That being said, I did get it to work, and it works well.
Build #2 (no pic available yet) was based on Madbean's "Sabertooth" PCB. Parts for this one came from a combination of Mouser and PedalPartsPlus. Aside from my LED not currently working for some reason, this pedal also works beautifully. I ended up housing it in a pre-drilled 1590, but if I were to do it again I'd drill one myself in the same orientation but put the input/output/power jacks on the top instead of the sides. This was built with the correct 4.99k resistor which most people sub 5.1k or 4.7k for.
Both sound great, although there are a few different values between the 2 of them (and Madbean adds a diode as well).
The Fuzzy Elephant build does seem to react less-than-ideally to my active bass, which I've seen reports of. The Madbean circuit does a better job in comparison. My first pedal also has a bit of wackyness at the extreme top-end of the fuzz pot, and I'm not sure if it is related to the pot or something else. I don't turn it up that far anyway, but it is worth noting. I have not played a real Woolly Mammoth, so I can't comment on exactly how well they reproduce the tone, but it's clearly close enough for a lot of folks.
From a build standpoint, the Madbean build is MUCH easier, especially if you have limited dealings with perfboard or veroboard. Personally, I can't look at one and translate it to another, nor am I great at taking a raw schematic and converting it to a perfboard layout, so having everything etched and ready to go can be a definite plus. Another advantage to the Madbean PCB or another PCB (guitarpcb has one, I'm sure others do too) is wire organization. The fuzzy elephant layout has wires going every which way, while a designed PCB makes things a bit more elegant.
The parts listed for the Fuzzy Elephant are readily available at all the DIY stombox suppliers, but if you want the 4.99k resistor, neither PPP or SB carries it so you'd have to order it from Mouser or another big supplier (I got all my caps, resistors, etc. from them for the build).
Both builds ended up costing roughly the same amount (IIRC about $75 for everything with shipping), but because of the PCB and easy layout the Madbean build took significantly less time. I probably spent 30 minutes populating the circuit board and maybe a hour laying everything out, prepping the wires, soldering everything together and installing it. I've seen plenty of people who've squeezed the Madbean design in a 1290 or 125 enclosure, but there is no way this could happen with the veroboard setup. It just takes up too much room.
I guess my conclusion in all this is to do whatever you want, although to me they sound so similar that unless you absolutely need to build it on perf or veroboard, just go with the Madbean or another PCB (or etch your own). If you do want to do it yourself, consider altering the schematic to get you closer to what the Madbean parts layout contains. To me, at least, it seems to be better for my active bass.
