I tried...I have/had several variable bass headphones. This, Beyerdynamic COP (both Over Ear and On Ear), Pioneer SE-MX7, Skullcandy Skullcrushers.
The only comparison from a musical style standpoint was the Beyerdynamic COPs. I'll stick with the over ears since that's probably what you are referring to. They are still very different headphones though. Beyerdynamic's COP over ears are like the DT770 although not as good but with more sound profiles thanks to the bass switch. The bass is looser, flabbier I guess could be a word to describe it. Some may like that, some may hate it. HD630VB's is a tighter more accurate bass sound. The beyerdynamic's offer a more forgiving sound. The HD630VB's are harsher and more accurate. The beyerdynamic's gently skew warm. I feel the HD630's are near neutral with the bass turned down. If not neutral...very close. The Beyerdynamic's bass is obvious every time you turn the switch up. The HD630VB's are far more gentle....the bass incline is minimal and tame. I really feel the HD630VB are for fans of Sennheiser's neutral headphones who argue over too little or too much bass. This is Sennheiser's closed back way of saying, here have the best of all worlds and go portable with it too. Even with Sennheiser's bass turned all the way up. It's in no way as bassy as your average ultra bass heavy warm/dark headphone. It's not that way. As opposed to the Beyerdynamic COP which with the bass all the way up is bloated and huge. I think the Beyerdynamic's soundstage is better. I frankly didn't feel the Sennheiser had much soundstage at all. Opinions vary widely on that I notice for both headphones, that's my opinion. Also the Beyerdynamic COP over ears clip at loud volumes while the Sennheiser HD630VB does not. Trust me, I listen at medium and loud volumes. I notice these things.
The Sennheiser HD630VB's weren't to my taste. Yet, I did respect them for what they were. They are sound wise the classiest, most tasteful variable bass headphone one can own if your an audiophile. They are the closest to neutral bass variable headphone I've heard. With that said....still not for everybody. It truly is a headphone to try and decide on your own. Too difficult to explain, opinions will vary too widely. You gotta try it on your own and make your own decision.
I have to say the HD630VB surprised me at Canjam. I expected something like the HD600/650 but a closed variant and that wasn't the case. That doesn't mean it sounds bad though, I'd love to try it at home to get a better idea of it. It seems Dave (who wrote the latest HFN review) also had to get used to the idea of it being different than the HD600/650.
Has anyone had the chance to compare it against the Beyer COP which also has variable bass?