The SIG Four Star is a very nice plane that is easy to build. If you feel safe with take-off, flying and landing your present trainer, you will have no problems handling the Four Star.
Another aircraft that is just about as easy to fly, and more capable when it comes to aerobatics, is the SIG Somethin' Extra (SSE). The SSE is available both as a kit and an ARF.
If you have the slightest inclination towards building your own aircraft, the kit is the way to go. It builds like a dream and the flying qualities are very good with no bad habits at all.

/Red B.

P.S. I noticed that your trainer is a .60 size and presuming you hava a .60 two-stroke engine (or equivalent four-stroke), the Four Star 60 may be your best option as you can continue to use the same engine in the new model. A .60 is too much engine for the SSE (at least if it is to be used as an "advanced" trainer). D.S.