Some time ago I built a Mudbunny with sockets for all the parts, with the intention of giving the different permutations a try. Well, that never really happened (been using it with the VRH specs now for a while, pretty good) but this afternoon I tried out a number of different transistors in the circuit as a small start in my search for The Ultimate Muff ;) Thought I'd post the findings here for all you Fuzz-lovers!
2N5088:
Slightly dark, smooth, not too much gain, liked it a lot for leads on the neck pickup
2N5089:
Sounds almost the same as the 2N5088, but with a bit more gain
BC549C
A bit brighter than the 2N5088/89, about the same gain as the 2N5089
BC550C
Also a bit brighter than the 2N5088/89 and higher gain than the BC549C, very cool for powerchord sludge
MPSA18
Harsher sounding than the others, but that can be easily remedied by a twist of the tone knob (either on the guitar or the pedal). To my ears the most gain of this bunch
I also have some BC182L's (and a lot more on the way) but those required some subtle leg-bending pin-out wise, which didn't seem like a good idea after last nights beer consumption ;D
I'll be doing the same thing with diodes, the different BOMs and more transistors soon, so if you have any requests or suggestions, please post!
Paul
http://juansolo.demon.co.uk/stompage/schematics/Misc/Muffs.xls
Suggestions ;)
You'll need to open that in Excel to see the notes and the Mayo schematic it refers to is this one: http://juansolo.demon.co.uk/stompage/schematics/Skreddy/Mayo%20Schematic.png
Pretty sure the Mudbunny parts are correct.
I've been researching this too. Apparently, there isn't much change unless you get below 100 hfe.
see this thread http://stompboxes.co.uk/forum/viewtopic.php?f=10&t=13565
Also, see this similar chart (to yours, juansolo) http://www.flickr.com/photos/thetonyballs/6841035924/