well first off, a 520 is going to wear out faster than a 525...
i went to a 520 chain on my gixxer and it wore out in like 6000 miles or something like that... its not very durable... i have a 525 on my gixxer now and i believe a 530(whatever is stock) on the 929...
as far as it hitting ur swingarm if u go down, who is telling you this shit, just reajust the rear wheel axle to make the chain have the proper slack and u will be fine, its not like it makes it spin on such a small area that the angle between it and the rear sprocket will cause the angle to hit the swingarm...
1 down in the front wont cause any ill effects, and if ur changing your chain at the same time, even better cuz u can cut it to the appropriate length, which is for every tooth u go down, subtract one link from the stock chain, and every tooth u go up u add one to the normal chain length... on my gixxer im using the stock chain and im 1 down and two up, length is great, i didnt have to move the wheel back that much at all, so it worked out fine... whereas on my friend he just went down one in the front and if the chain stretches a bit its going to have to be replaced due to the extra length...
like i said, im 1 down, 2 up on the gixxer and i ride on the highway all the time, im not riding at 10k rpm and higher constantly either....
my 929 is 2 down in the front, no problems with that either...
do whatever u want dood, there wont be a problem with anything, 1 down 2 up isnt that much of a deal really...
-icehot113