I'd love to get a sense of the percentage of people using X2 that are happy with it's performance and stability? 

So far so good.

Seems alright so so far! No crashes except when using a whole outfit of console emulation.

I had some problems initially, but I did some serious clean up of my computer, including checking my C: drive and running a full virus scan which uncovered a trojan that was hiding on my computer. I also ditched a ton of VSTs from various sources that I wasn't using and I am now sticking pretty much to the Cakewalk supplied plug-ins. In addition, I removed some old versions of software on my computer and cleaned up the disk drives so they had a lot more free space. Since then, its been much more stable. I think some of the instability people are experiencing is due to running 32-bit plugs in the 64-bit Sonar. I suspect bitbridge is not always able to bridge the gap. 

I'm happy. Had a couple weird crashes but I haven't installed the quick fix yet and I'm sure the first full patch will shake out most of the bugs. Take lanes are great. TH2 is great. The new time ruler stuff is great. I haven't messed with much else though like Breverb, R-Mix, console emus or any of the other goodies but that's coming soon. I run an i7 2600k, 16GB Corsair Vengeance DDR, Caviar Black 7200rpm drives, ASUS P8Z68-V PRO GEN3 MOBO, Win 7 Pro, Focusrite Scarlett 18i6 and the system has been optimized using the Sweetwater optimization guide minus a couple of Sonar specific steps. Cheers.

It's ok so far. But I'm having an issue with now time being weird (not snaping to where I want it or where it should be pre preferences) the dimpro thing (which seems to be some can reproduce, but not all) the TH2/prochannel recall crash (they must be working on that, totally reproducible)  and some general annoyances like clicks when turning certain things on (mostly prochannel)

But it's been pretty stable so far. I admit, I'm not a power user yet though.

50/50 here.
More crashes than X1, bugs that need fixing.
Some nice new features.

Extremely happy - so far - but my use of the full feature set is limited, so take it for what it's worth.

Update: Less happy since working today with Take Lanes and having some trouble with them. That's to be expected. If I can make my workflow follow the "Happy Path" it's fine, but there are some quirks here that are a little ugly. I still think, for a v.1.0 feature, it's pretty solid.

happy

regular crashes here, say one or two a day... vs one every two months with x1.. activities that are prone to creating a crash are:
1. changing midi devices in preferences
2. auditioning audio content

like beep though, happy enough and sure that the first update will make major improvement