520 helps get rid of a bit of unsprung weight. Its a good upgrade I plan on making the upgrade myself.

You won't snap a 520, don't know where that dewd got that Idea from.

Alum are lighter, the drawback is they don't last as long. I had alum sprockets with my older bike with PM Wheels. No other probs other than longevity.

Pay close attention to your ratios when changing your gearing... 15/45 gives you a ratio of 3.0. a -1 front & +2 rear changes your ratio dramatically on any given bike. It may cause it to rev too high at crusing speeds & take a bit of top end from the bike... if you are cool with that then go for it... just trying to help you know what you're actually doing...