actually.. they don't really dump their guns, they actually only switch because of better sponsors. sponsors offer more $$ and equipment so that the pro's can use them, it's basically advertisement saying: so-and-so uses this gun and he's a pro, if you want to be pro, you should use this too!
it's like what ed poorman told me over the summer. they all used to use cockers and eventually switched over to angels because of sponsorships. he agreed with me that cockers are the best guns out there but the only reason he really like angels more than cockers wasnt because of the sponsorship but because the angel didn't need to be as heavily maintained as a cocker