Another update:
So, I bought that growler back in May 2015. I was excited to bring it into the Mammoth Brewery and get it filled. They told me that they don't fill unmarked growlers, only ones that they sell with their logo. I asked if that was a state reg local reg or company reg and the person behind the bar said a little of each, but they were working on it. I went in a couple of months later and they still wouldn't do it.
So, later that summer on a visit to Kansas Mike and I went to a pub/growler fill station where I met Jeff (the one who is coming back to CA to help me lay laminate shortly)

I forget how many beers they had, it was like 20 or 30 and your first 5 tastes were free, and it was a good-sized taste. So, I picked a beer, got the growler filled and left a day or two later for a trip to Wyoming. Where I couldn't get the top off. Finally using the screwdriver tool on my Swiss Army Knife I was able to break the seal and get it open. I thought maybe it had something to do with elevation change or something.
And then it sat around, partly because I forgot I had it or forgot to bring it to get filled, partly because of size/weight. Then yesterday I went up to Bishop for a check-up with the orthopedic surgeon who did my shoulder and a couple of hours fishing in the afternoon. I ended the day with a burger and beer at the new (about a year and half) brew pub called Mountain Rambler. They gladly filled my growler with their very tasty Notch IPA which I brought home. I had a half pint of porter with lunch - also excellent. Annnnnnd, I couldn't get the top off without a screwdriver. Annnnnnd, it wasn't the elevation change because I opened it three times last night and just now tonight and each time it took a screwdriver.
So, this will be going back to REI. I only used it twice and both times it did not work as it should. Fortunately, although REI recently changed their return policy to make it more restrictive, this was purchased less than a year ago so I will get my 50 bucks back. Now the question is to return it and get one of the other growlers on the review or not. I this this would be pretty cool to have if I frequently filled growlers, but I don't. So, I'm going to get my cash back and buy a bunch of beer. I can always wrap a few cans in a down jacket and keep them cold. I'd be interested in hearing from anyone who got or gets one of the others though since I still think this is a pretty cool idea.