What movements are you talking about? The first movements, or the whole thing? I think greig 1st movement stands alone better than the SS2 first movement. The last movement for SS2 is great, and might be a better choice for a competition. As for difficulty, I personally find the first movement of the Saint-Saens (which I am trying to polish and get up to speed) fairly difficult because my octaves are a mess, and my left have arpeggios need work. The grieg doesn't sound all that hard (1st movement) except for the impressive cadenza, but i'm sure its harder than it sounds.