Hi Neil,
I started running a 16/52 set up on my 01 501 when I wore out the first set of 15/48. There were two reasons I went with this set up. 1 was to pro long the components life, and 2, to keep the chain wheels in line with each other as much as possible to make for better suspension action. This was a trick used by MC, I'm no MC but hey, if he thought it was a good idea then I figured it was worth a try. The theory goes something like this, there is less binding when the wheel is at extreme deflections and is supposed to make the suspension action smoother. Next time you have your shock off do a bit of experimenting and you'll see what I mean.
On my 04 550, the bike came geared 14/48. According to the book it is supposed to be 15/48. I never knew this until it was time to change out the components and that's when I discovered it. I was actually attempting to set it up with the 16/52 arraingement but, I couldn't get the chain to fit right. One link extra was too much and one less link was too little. If I was running a lower profile tire the 16/52 set up would have worked. However, I run a Pirrelli 120/100 MT 18 Heavy Duty tire and this tire is quite tall, and works good for the desert. At this time I am running a 15/52 set up on my 04 550. This is a great combo as far as I'm concerned. First gear is a real rock crawler, and sixth gear WOT gives about 100 mph. With this set up you can cruise comfortably at 60mph without revving too much. When the time comes to change out components again, I will go with the 15/52 set up again.
So, to get to your point. On the 01 bike I had to modify the chain slider to get enough clearance. On the 04, no modification was necessary.