Well…I don't know any manga / anime fans besides myself, so obviously I don't know any other One Piece fans.
But if I had to guess, I would say those who supported the series in the dark years it was abandoned due to 4kids and have currently bought all the speed-up volumes are those like ourselves; older fans in their teens / twenties (I'm 20) who followed the series online and were up to date. I don't really think the younger or more casual fans jumped on board with the speed up that fast when Viz rushed out 30 volumes.
Also, One Piece is in a 3 way tie for my favorite manga (along with 20th Century Boys and Fullmetal Alchemist), and while I don't think it's a masterpiece like the 3 I just mentioned, I do like Naruto. The story has more depth than most shonen manga, more plot twists, and generally, I think it's been Part I quality again ever since the Pain Invasion. I will agree the Sasuke arc was very flawed, but I don't think that was enough to ruin the series.
Bleach, on the other hand...I think Bleach really kind of sucks now. The current arc is absolutely terrible in my opinion....Hueco Mundo was boring as heck. Arrancar arc was mediocre. Up through Soul Society was pretty entertaining as a pure action series with a semi-decent story though...the Aizen plot twist was pretty decent even if it wasn't anything like what Urasawa could pull off...the art is nice, character designs are interesting, and up through soul society, the series was pretty decent for a regular shonen action series. Way better than something like KHR!