We use contract pricing quite a bit and have never noticed a single instance of incorrect pricing. We've been using DBA for over a dozen years and Evo since shortly after it became available.
 
You do realize that there are several different ways to do pricing/discounting and that they don't work in conjunction with each other? In other words, there is a hierarchy and where ever there are two or more possible methods of pricing the one highest up the list takes precedence.
 
I'm not sure from what you write if you are getting different results in Evo versus DBA (classic)...?