I honestly don't have any issue with the fit of the DDM's. I sold another guy on them by lending my pair out to him, and he had no issues either. I use a pair of MEElectronics M9 double flange ear tips with them though, which extend the phones out from your inner ear. Aside from improving the sound quality, it totally minimizes the contact of the phone's housing with the concha of my ear eliminating any fit issues. And it's not like I have super big ears anyhow, I'm a 5 foot, 7 in. tall Asian dude.
I just dislike the FX500's at times harsh nature, due to the treble sparkle. They also feel a bit congested and thin to me too due to the recessed mids and average soundstage. I don't have those issues with the DDM's. I'd say that the soundstage possesses a lot of depth so the placement of sound is a lot more satisfying to me, and the vocals sound a lot more forward and upfront which I prefer.
As for the hifiman RE262's, I don't believe that those are available for sale from Head Direct just yet. They were originally given out as freebies with the HiFiMan DMP. As such, you'll see them being sold on Head-fi periodically and in a lot of cases, unused. I've seen them go for as low as $140. The sound is truly AWESOME though, the clarity, resolution and attack from these phones is very good. The only thing is that you have to drive them with an amp to be suitably impressed. That and... the build quality isn't going to win any accolades. They look pretty ratty next to the DDM's and especially the FX500s. It could just be an isolated incident, but my pair went south roughly two weeks after owning them, and Head Direct have got a replacement in the mail for me as I type this. Luckily, the guy who sold them to me stood behind the warranty for me.