Jean-Marc, my experience with circlips (mostly as found on old English motorcycles) has been that:
(i) the easiest ones to remove are those which have little ears on them with a nice wee hole in each, so that you can use circlip pliers; and
(ii) then there are the circlips which can be removed by inserting a thin blade under one end, such as a quality screwdriver. These circlips may have a raised end to make it easier to insert your pry blade, or there may be depressions in the housing. Either way,I've found that they can have a life of their own, and make a break for freedom if they require any significant leverage. Dunno how you approach such things, but I'd feel much better knowing you're wearing some eye protection when you pry the little critters loose. (Or: maybe cover the circlip with your free hand, or with a plastic bag?)
Good luck!