The PSR's do have a smaller key as compared to true full sized keys. Maybe it's the keyboard makers way of saving money on plastic. When I was in college I would often visit our music departments "piano teaching lab" It housed a really nice CVP, and numerous smaller Yamaha digitals. After playing on them I'd go back to my dorm room and play my PSR, and geez how cramped I felt.. The keys are smaller, but you get used to them. If you're going to be moving between a digital and a PSR often, you'll notice the differnce.
Squeak
_________________________
GEAR: Yamaha MOXF-6, Casio MZX-500, Roland Juno-Di, M-Audio Venom, Roland RS-70, Yamaha PSR S700, M-Audio Axiom Pro-61 (Midi Controller). SOFTWARE: Mixcraft-7, PowerTracks Pro Audio 2013, Beat Thang Virtual, Dimension Le.