I think that may be the case. As best I can figure from my logs, the E9 was out about 10 years before the E12 and, until the E12 issues started cropping up, I don't remember widespread problems with the E9s. This is just what my flawed memory came up with.
I had an E-9 cato fairly spectacularly this last weekend. Blew both ends out about 10 to 20 feet off the ground. Loud boom and lots of sparks. In a saucer so no damage. I have had enough of them blow that I only use them in saucers.