I've always found that Zipwax + sponge combined with plenty of elbow grease does the job fine. I'm loathe to buy loads of different car products for different purposes but that's just a personal thing.
I use Halfords alloy wheel cleaner, its a spray foam leave it on for a minute then come back with bucket of hot water and sponge and get at it with gusto. also what helps is if you get one of those sponges from the supermarket with the green pad on one side and the yellow spnge pad on the other. the green bit (stiffer bristles) will get it off no problem without sctraching your alloys and is flexible enough that you can get into the little places that a bigger sponge cant. if its dirt that has been built up for a while then you might need to repeat.
no its not that hard on the alloys, you use them for doing the dishes too. i usually buy one wet it down and squish and squash it a bit to loosen it up and then use it on the wheels.
this is the link to some of the sponges that i use. never noticed any scratches on the wheels after i have used them on mine. dont work for killeen also.