Hello Spike, I've been using an x-50 for about 5 years, I usually don't change discrimination based on coil, I adjust for the site and how much time I have to hunt. I try to hunt in all metal most of the time.
You will notice a slight shift in TID, and the HF coil hits hard on nickels, I have used the 5x10.5 the most, it works well in trash.