I have no experience of Arctic Butterfly and have only once performed a wet cleaning (lots of puffing, though) on my 30D, which went swimmingly. On that basis I would hardly call myself the world's most experienced sensor cleaner.
However, my brother in law is a professional photographer (that doesn't make him a professional sensor cleaner
) who recently used an Arctic Butterfly to clean his Nikon D3 sensor and ended up with smears all over it. He believes it was from grease and whatnot left in the mirror chamber, rightly or wrongly, as part of the manufacturing process. Of course, maybe he was just unlikely, or maybe careless, or perhaps Nikon are more liberal with their muck spreading than Canon, but it's a cautionary tale about taking care not to pick up muck and spread it around and end up making matters worse.
FWIW, when I performed the wet clean on my 30D, the sensor was by no means filthy but puffing alone was insufficient. I studiously followed the instructions to use only two drops of Eclipse liquid and allow a few moments for it to spread and partially evaporate, and then tried the one pass forward and one pass back technique as recommended. That did not get the job done properly. The official next step is to get a new PecPad and take another run at it, again once forward and once back. I thought "bugger that" and just added one more drop of fluid and rubbed gently with the re-moistened original PecPad over the sensor, in much the same way that you might clean any piece of glass - back and forth, a little bit round and round, just a general wiping all over the sensor surface. That did the trick beautifully. I know that's not the recommended approach and there is a risk of scratching the sensor if a bit of grit gets picked up and then rubbed all over the thing, but I took a calculated risk and it paid off. So I'm not advising anyone to follow my approach but just mentioning that using common sense and a suitable degree of respect for the sensor worked just fine for me without fiddling around changing/discrading PecPads etc.. I shall use a fresh PecPad for the next clean, but based on my experience to date that will not be for some months. Usually a good puff with the Rocket is plenty.
My 10.5 month old 40D is yet to need a wet clean and I've probably only had to puff it two or three times since last September. The built in cleaner, plus my own care when changing lenses as kept things very clean so far.
