I like the piano sound of the psr 550, but I do not really need all the tracks and sequencing features, I also do not like the smaller key size it has, is there a synth in the $5-600 range that has better piano and organ sounds (which is basically all i use) than the psr 550 and has FULL SIZED keys that i should consider?? I cnnot really go anywhere to compare the two so you input is very helpful.