I'm still a bit puzzled that a closed can is considered a next step for an open one. Don't get me wrong, I'm really curious about the X00 and I've been so close to joining one of the drops several times but I've always been more interested in open cans and IEM's so I've chickened out every time. I'm not a bass head and really love the huge soundstage in all directions on the X2 so I wouldn't want to trade even a bit of that for more bass.
One thing's for sure though: I'm really looking forward to hear the impressions and comparisons between the two from you guys that also really enjoy the X2's.
Sorry for the rant
I share your concerns regarding loss of soundstage and space. I am also more into opened back full size cans. Not that much into IEMs though. Bass is obviously important to me if you look at my headphone choices, but I wouldn't say I am a basshead.
Recently I tried Nighthawks (semi-opened) and had the same concerns of loosing space. I was right, NH does have smaller space and soundstage than X2. But NH is better in other things, like bass. (Cleaner, expands lower, more detailed, more present.) Eventually I found I can enjoy NH and X2 on the same level, just the experience is a bit different.
I let the NH go, as I couldn't justify its price, and I also didn't like its upper mid-range, lower treble. Not because the space was smaller, but it just sounded too unusual to me. (And already paid for X00s too.) To be fair I have to mention, NH was a more intimate, more engaging listening experience, but X2's spaciousness and airiness on the other hand equally likeable attributes.
Also, even though X00 is officially closed back, owners say it is more like semi-closed/semi-opened. It does leak and doesn't isolate much therefore you also have quite nice space.
Anyway, I am just telling my NH experience as a proof, that a semi closed (closed) headphone can be as enjoyable as an opened one, just slightly different. (Obviously not a £200 closed can, but rather the £4-600 price range.) NH convinced me of that.
So I am hoping X00 to be a "better NH" for my personal taste and preference.
Whether I will sell my X2 or keep it, that is another question. I have no idea at the moment.