The question of whether there is a point to it or whether it is useful in the modern era or whether there is any worth `worrying` about it is entirely subjective opinion. I wasn't asking for everyone's judgements of the validity of the question, I just wanted to know the number. Flameduck's response is interesting but a worst case scenario for sure. It's good to know that 16 registers is about a reasonable minimum. Thanks for all your observations.