Used it for my Fazer and always bought it up a treat
I've used it on the GS in winter, great for getting off the grime and you don't have to spend ages cleaning, just rinse off.
1 litre bottle lasts quite a while and reasonable price.
Be very careful using this stuff, a couple of weeks ago sprayed it onto my old r45 then went into the house to answer the phone , 15 mins later it had dried and turned the paint work a faded red that wont polish out, good job it was only my old bike.
Hovis
I use Castrol GreenTec - which is what the BMW Off road school use. It's excellent, if expensive (but not as expensive as SDoc 100)
If the bike's not that dirty I dilute halfords car wash 50/50 with water and spray that on. You need to brush that in though - not that that's a big job on a bike!
I use Sdoc 100 and its really good at getting your bike clean with minimum effort. Cleaned the bike 4 times so far and still got around half the bottle left
Look out for offers on it as recently I've picked up quite a lot on the cheap with buy one get one free deals (e.g. coupon in MCN last week) which works out at £7 at litre
I thought it was the mucoff that has dulled the black on the head/barrels but I strongly suspect it is the sdoc.............
Bike was like new 2 months ago and now looks 'used' on black parts
Are the heads/barrels painted 2 pack or powder coated on 1200GS's?