I don't see where the Something extra would be that much more difficult to build than the 4*.
As far a flying the 4* it's a great first low wing plane but loves to float when landing, will do some basic aerobatics and is a good second plane.
The Something extra is a great third plane and capapble of a lot more wild aerobatics and with the proper set up will do 3D.
You can improve both your building skills and flying skills with the 4*, then jump into the something extra. Or you can skip a step and go right to the Something extra and set it up with moderate throws for starters then progressively more throws as you improve on you flying.
Just my $.02.

Happy Flying


Tom