Opera, Chrome and Chromium are based off the same engine which is a fork of WebKit. If anything competition has gone down the last couple of years with WebKit based browsers becoming the standard despite its bugs & non-standard behavior. It reminds me of IE6 in its heyday.
No web developer worth his salt writes code for any one browser. You write code to the standard and test in browsers. Anyone doing differently should be fired on the spot. I'm not aware of any professional web developer who does that.
