My sister bought a Sansa Clip + after recommendation from me. I decided I'll listen to it with my RE0's. It sounded warm, maybe a bit veiled. But I can't clearly remember, didn't play with the EQ at all. It wasn't rockboxed. I'm comparing this against my iPhone 2G 16GB, the same recording that I used with the Sansa (except encoded at the same bitrate in FLAC form) that I heard sounded less warm, and wasn't as veiled, the highs sparkled more.
I don't think the Sansa Clip + sounded audibly 'worse', however it did sound different. This is like comparing two high end headphones, they always both have their traits and pluses, but they are usually level and very consistent at that when it comes to quality. But, after saying that, I can tell you for sure that the Sansa Clip + shows up to be excellent value for money.
However, because I prefered the iPhone 2G's sound, I will have to vote that I liked it's sound better. This is very much a subjective hobby and while I found quality to be the same. I found that I liked the iPod sound better.