The Star Coyote has a different feel and flight of the Champ or the DX. I know because I have all 3. It makes a fantasic approach disc. You can even putt with it. Try one. If you don't like it, I will buy it from you.
i doubt you'd want to pay shipping from Finland to the US.
a new disc is only the answer if the disc that was being thrown was a vastly inferior product to even the "average" performance discs on the market. e.g. being able to throw an APX 150' takes some mad skills and it's probably easier to get a different disc.
aside from those cases, the true improvement happens with form and technique, which will yield better results with EVERY disc and not just one in particular.