First off, Ryu is definitely tourney viable. He's the best all around character in sf4, if you have solid fundamentals then you can win with him. Heck, John Choi barely plays the game and took 2nd using Ryu.
Now, if you're set on Elf, you HAVE to get the execution down. He's very execution heavy, and also very mixup heavy. A lot of your game is going to be getting in range where you can cancel a normal on block/hit into a splash/tortilla to get them on the ground to get your loop started. Keep in mind that elf is a lot harder to use than Cammy. Cammy's pretty easy to get a hold of, so whatever work you put into her, you'll have to put double time into Elf. Now granted, some of that learning process was due to the game being new, so you won't have to replicate those difficulties with another character since you're more familiar with the game, but you'll still have to put in a lot of work.