Good choice. However, if you get the urge to attempt the Extra, get your instructor to hook you up to a buddy box, get it up high, and let you take over. You can get a feel for the Extra, with minimal risk. I learned on a PTS Mustang (low wing trainer/sport plane), and had a Seagull Yak 54 that I had intended to fly as my second airplane. After I had gotten a feel for the Mustang without the training aids on it, and with an OS .55AX (more powerful motor than what comes on it), I had a club instructor hook me up to a buddy box to let me get a feel for the Yak. Let me tell you, I'm glad that he was there. Yaks, Extras, Edges, Sukhois, etc... can be very "snappy" and have some bad tendencies that someone with little experience won't know how to counter (I was in this boat when flying my Yak). I flew it on the box for about 3 flights, then was able to fly it solo (after flying a more advance plane than the Mustang, but not quite as advanced as the Yak). Just because I had a good handle on the plane doesn't mean that I was ready for it. After about the second or third solo flight on the Yak, I went up vertical, then started coming back down. Well, on my Mustang, I was able to "fly it out", but when I tried that on the Yak, it started to snap roll and stall and snap roll some more. I was 4-6 mistakes high (luckily), and started yelling for help. The instructor that had buddy boxed me on it came running, took the Tx, neutralized the controls to allow the airplane to build up airspeed, and saved the plane.
The point of all of this is that you should continue with your Rapture, and if you get the urge to fly the Extra, get it hooked up to a buddy box, then fly it like that at altitude. That will wet your whistle on the Extra, as well as maybe give you a bit of a "scare". Don't attempt to fly it solo until you are ready for a plane that may have some bad habits. Don't rush it, the skills required to fly the Extra will come quicker than you think
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Happy flying.