I have listened to the HD201s and for the price was very impressed. They dont have the bass emphasis of my PX200s, which surprised me because they are much bigger. But I prefer a more neutral sound where the midrange leads and bass and treble back up the sound. So if you are a metal, dance basshead my experience is that you would find them a bit lean. I auditioned them with a Denon AH D501 and the Senns won hands down for me. The Denons sounded flat with a very coloured sound.
I was listening to some Queen and The Kings of Leon in the shop and both had good clarity, rhythm and detail. There is a very limited soundstage and all the sound was in my head, but as they are closed back and for the price, I would not really see that as a major criticism.
They have nice large around ear cans and felt comfortable. The cable also appeared to be quite long.
I would have bought them, but Play.com have the Goldring NS1000s on sale at £50, down from £160, so I went with them instead.
Unfortunatley the music shop where I found the HD418s in, they were not working. I would say you you should have a look at the Sennheiser site and see what the specifications are for the two headphones. If they are similar, then there is every change the sound will be very similar, but the finish is different. I say that because I also had a listen to some HD205s at the same time as the HD201s and I could not tell a difference in the sound.