Yes, I have a hydration pack (not the same brand as yours). And yes, I use it: maybe a couple or three times a year. And though it doesn't get quite the same exposure as chain lube threads, the discomfort I have when wearing one, particularly on long, hot rides, has been discussed in many, many threads over the years. So unless you have something to add that's not been posted many, many times before, can we leave it as I don't want to use a hydration pack on a long road tour?