I had a few pms with newman regarding this issue but I'll reveal it here too.
I am still on v2.5.8. (Well, I was on v2.5.5 till last night

)
What I am more interested in, is that speed in flipping page doesn't change so my reading experience doesn't get worse. Does upgrading to 3.2.1 or even 3.4.2 make the experience less realistic?
It'd be nice to be able to switch between version on the fly, i.e. work with 3.4.2 and when you need to, go to 2.5.8. Obviously, not just these versions and not just Kindle DX. I have system images of my DXG for 2.5.5 and 2.5.8, in fact, before doing anything, I take a dump... hehehehe
I think I disclosed it for Kindle Touch or Kindle 3, when I was more active here, but: Has anyone found a quick way to switch between versions?