This slightly off topic, but 6 buttons across the face of your controller will help with the SF games, but you will still be left in the dust by anyone with a real arcade setup. Notice I didnt say arcade stick, because the act of having one, even a really good one, means squat. To take true advantage of it, you need to have it set up and secured to a stand that puts it at releative arcade cabinet height. Then you need to weigh it down, so it wont move all over the place.
I worked at an arcade for over 5 years, and played in area that is host to some of America's best players (California, valley area). I played fanatically and in tournaments whenever possible. I had many friends whom thought they could play just as well with a pad as any tourney player could with an arcade stick. The best way to show the how wrong they were was to just have them come to the arcade when the tourney SF crowd filed in to get practice. When they started to see all the things those guys pulled off, and how hard they laughed when asked if they thought they could do that on a home console pad, they kinda figured it out.