I would leave micros. I learned off of micros and honestly they arent that great. I learned off of a 3 channel micro which gave me false confidence boost then a VERY twitchy 3d capable Yak 54 micro 4 channel which was VERY hard but taught me a lot too.
You should move up to a larger 1100 wingspan foam glider. Great slow speed performance and great flight times plus some gliders can be quite aerobatic.
A radian is 3 channel but if you wanna go 4 channel take a look at AXN Floater Jet and The Bixler from hobbyking.
http://www.hobbyking.com/hobbyking/s...dProduct=18083
and
http://www.hobbyking.com/hobbyking/s...dProduct=18916
I have the AXN and it is fantastic and slightly smaller than the bixler. Bixler can fly slower and more stable but the AXN is faster and more aerobatic plus still stable enough for learning on. You will need servos and 30 amp esc, instead of the 20 they recommend. Plus servos are 2.50 bucks (the 9gram Orange HK servos). Plus you need a controller. I recommend the Turnigy 9x controller. Fantastic for the price and the receivers are Cheap both 8 and 4 channel. Plus you can always upgrade the Module later with a FrSky one which is IMO one of the best especially for the price.
And surprisingly they have the turnigy in stock in USA store.. Thats really rare lol because its normally sold out all the time at any warehouse..
http://www.hobbyking.com/hobbyking/s...dProduct=19673
[youtube]http://www.youtube.com/watch?v=2WYSfJQZk1o[/youtube]
here is a video of my AXN onboard. The AXN so far has been my favorite plane and owning balsa and foam... I still love my AXN the most. It fits in my trunk easy, uses 2200 3s batteries (common), and i can get almost 30min run times if I go for thermals and take it easy. Really satisfies my hunger for flight, easy to balance, takes a camera with ease (but bixler can carry more load period making it popular for fpv), and the plane just flies so well and takes hard landings/crashes with ease.
Very tough.
[youtube]http://www.youtube.com/watch?v=tzjdbvSHMUc&list=UU3gDybnd8cPYV0I_eH9fB8A&index=6&feature=plcp[/youtube]