I have thought about ditching one disc up front I also thought that by doing this I then have a spare disc to replace the worn out one and a set of spare pads, if i did this I would convert to stainless braided hose. Chris Scott thought that 2 was a bit OTT. I think Yamaha put 2 discs up front as a visual appeal.

As far as the rust goes if I leave my bike outside for any length of time without use I would give the whole bike a good coating of oil, yes even the discs they only need a quick clean before next use.