Actually, I would think that using a or b could make a huge difference in some products depending on the twisted pair that is twisted the most. We have switched to B but always check to see what each product requests. I know that I tried to use a balun with A once and could not get it to work. The product did not mention anywhere that I needed to use b but once I made it B, It worked. Just for kicks I tried a again and tested everything. Didn't work. As far as Onq, I am pretty sure we used B on the last few jobs we did and had no issue. Sometimes it just does not matter. Sometimes it does.