Okay let's see. Ingredients: Whey Protein Isolate, Cocoa (3%), E955. Cut to Google... yup that's sucralose. Is that a problem for the average Joe?
With the L-Arginine I think it's a good idea to start at the low end. For one it can cause stomach pain in higher doses, and secondly, too much NO in the system may be dangerous in the long term. I'm looking into this in the next week or two. I think 1g just before exercise should be plenty for starters, but I think around 3g is the most commonly used dose. I'll let you know how I go, but I've also have that beta-alanine which contributes to NO production as well. I don't know enough about all this as I should (especially any negative side-effects), but then again I haven't even taken my first L-Arg dose either.
By the way, there seems to be a few hits if you search for "flavourless whey protein". Nature's Best Perfect Isopure sounds promising: "Pure Unflavored Protein With Zero Additives!" Maybe have to order from the US?