Inverurie and Kintore can be covered pretty well without waders.
In fact some of the better stretches often have the best trout at the nearside bank so casting along the edge at your feet is very effective.
That said other really good bits are only accessible by wading and as Fred says, use a staff the Don is a nasty place to wade without one.Lots of slippy rocks and sudden potholes, especially in the good bits
So waders are an advantage but not a neccessity, i'm not familiar with Alford, so couldn't advise.
Sandy