Good quality, little small - Mystery Ranch Quick Draw GPS Holster

I have the giant old school Garmin Rhino 650 so when trying to fit it in this pouch it was a challenge. I had to reef on the elastic strap to get it to go over the top. I wonder with smaller GPS units if there's any risk of them falling out if the elastic stretches over time. I may use the pocket for my iPhone since it seems to fit nicely, but also a little concerned of it falling out although it probably wouldn't.