In reply to Andy Cloquet:
It really depends on the route and time of year. Many routes will have old gear every 25m if they are used in decent. Plus it's snow level dependant, you might have masses of options or very little of the insitu.
If you plan to climb stuff that is mainly pitched climbing, ie harder routes, then 60 has some slight advantages, but if you are only on easier ground and will spend loads of time in coils there is no gain in practical terms, but more weight and bulk to share between you. Horse for courses, there is no reason why any of the standard routes won't be entirely possible with 50s, they've been done that way for decades.