This is an old post with no answer. I used Engine Ice in my Honda VTX1800 which requires no silicates or phosphates because it is an all alloy V-twin engine. I was very happy with it because the product is wetter then regular coolant, which helps with the heat transfer efficiency from metal to fluid, and it has worked extremely well in that application. It is used religiously by many leading motorcycle racing teams. I know in the Honda world, many use it as "the best of the best". So as you can tell, for my Honda I'm pretty sold on the stuff, but would not use it if it is bad for the Beemer.
So I asked the company "is it also nitrite free", and the reply is:
"Yes it is, no problem". The reply came from the president of the company, David Kimmey.
I'll be buying some to use in a coolant change in the next few weeks and we'll see if it helps the temps a little on hot days. It did in my Honda.