I was a late-comer with Wackys when I was a kid. I didn't start collecting until the 6th series. That is why the 6th series is very nostalgic for me. I know a lot of people don't really care for the 6th but I love 'em. I think Mold Rush is one of the best Original Series puzzles. I remember that the 6th series was in stores for what seemed like forever. When the 7th series came out, I almost didn't buy any because the packs were still blue and I figured they were still 6th. Then some friends started showing up with 7ths so I rushed down to the dime-store and bought a bunch of packs. I was in the fifth grade and one of the most distinct memories I have of the Originals is when me and another kid were looking through our 7th stickers and we discovered that we had two different versions of Grime. I remember that he had one version and I had the other but I don't remember who had what. We made some trades so that we both could have both versions. Before the 7th disappeared, I know that I had a least three copies of each version. Then my mom threw out my collection when I left for college (but that is another story)!
I ended up collecting 6 thru 9 but never saw 10. I had 11th and 12th and then finally 14th (all tan). In fact I never knew that there were white-backs until 1999.