I have bought some alpro. Just the plain stuff, not unsweetened.....lets give the guy a chance. Only had a chocolate variety, and it was quite a big tesco we went to. Bought choc snack packs, not the full one. Dont really want him to only drink chocolate milk if I can help it.
I think a lot of this switching milks is a psychological thing for DS. He has not been keen to try something new. Today I told him that we werent allowed to get formula any more from the chemist, and please would he help me choose a big boys milk. He seemed ok, but I am expecting some resistance when I try it tonight. But once this pack of wysoy is gone....its gone.....thats it i have made up my mind. Showed him the mama and baby on the formula, and he seemed to understand that boys who wear pants (sometimes!) and have BBB's ned BigBoy milk.
Update: it worked! he took to the BB milk like it was candy just like you said mashi! So when I am ready, I can just do a milk trial, and give up with the forumla completely. I feel a weight quite literally lifted from me.