^^^ These things are never a problem - until they are. I have had to apply some gentle plier pressure to tighten up the connectors on a lot of devices that took 9V batteries over the years, and I prefer not to have the additional point of potential failure if it's not absolutely necessary. The size difference is negligible, in my opinion (who can't get a 9V battery box into a venue?)...And, personally, I would rather deal with a company that has fast delivery and efficient, non-churlish customer service...YMMV and all that...