Thanks for the responses, guys. I have a mixed lot of film to process, some 35mm, some 120. One of the 35mm rolls is ancient -- been in my freezer for years -- and doesn't really contain any shots that I'd regret not turning out. I could use it as the test roll, I'm thinking, but then I'm wondering if, because of its age, it might give me results that I won't be able to apply to the other rolls. Hell, none of the rolls contain anything critical, far as that goes, so I don't mind doing some testing on all of them. I'd rather play around with the kit and the film than just toss the kit and start over.
I've heard the same thing about blix being bad, but I have some slides I developed with a kit that used blix back in the mid-80s -- about 28 years ago or so -- whose colors are as good now as they were when I first developed them. So, I personally don't assign any merit to the negative comments about blix.