I am purchasing a new digital piano.. I am a beginner and want to make 1 purchase. i cant decide between the Previa 870 or the CGP700.. I will of course be adding the pedal set to the 700 if i go that route. I suspect the 870 has better sound.. but i like the interface on the 700.. hoping my 15 yr old stepdaughter get interested in playing so i was thinking the added bits on the 700 would appeal to her.. . any help?