I to have been using Pro-rated for a long while now, but haven't had any mixing problems.
What I tried in the past and also just recently ordered for a change of pace is EAS simply whey. Available at vitaglo for $20.78 5lb tub (free shipping). I remember it mixing and tasting good, also low in carbs/cholesterol. If you want I can get back to you when I get it in a few and let you know. Just PM me.