Not claiming to be anywhere near an expert so take with a grain, but my several cents worth, in no particular order...
1. I agree with some of the other comments, and was one of the drivers in my recent decision; was that on my previous wing, I asked myself if I was consistently using bar to get around. I was. Between thermals and on-glide I used it almost exclusively to get to point B, because I was getting frustrated by it's lack of penetration. This meant I was wringing out the performance of my old wing and organically ready to move up the performance curve. Something to consider: your bar usage.
2. Ask yourself not only what your ultimate goal is (to fly more XC as you mentioned), but ask yourself what are the steps to get there. If your current glider satisfies the equipment needs of those steps then why move upward in terms of performance (b/c you risk safety as you move up the spectrum)? If you current glider level won't let you achieve those steps, then maybe a different glider will help. Also, what is the "bigness" of those steps? Our sport requires small steps.
3. Do you have your reactions-comprehension-glider dialed-in wrt emergency maneuvers/SIV? Do all the maneuvers in your old glider. When you have your responses pretty much perfected, then that's another point of thinking about upgrading. So, the question you could ask is, do I have the emergency response skill set to fly a hotter wing? Do I possess those skills for a lower, but gentler, version?
4. Wing-selection wise, The upper ENB category is now blending with the next higher category, which means the reactions and active piloting requirements between a high ENB and low ENC are becoming similar... some wings may get a better score in one area but not be great in another area. From a mostly academic and lab-type setting of glider certification, what they test are not real life conditions and you will hear stories of wings reacting very aggressively, be them ENA or END-CCC because of those real conditions. Like Santa says, a spider can come along and tie our glider in a knot whenever it wants. Not to scare, but to project prudence. However, I do feel that the lower-mid ENB (e.g. Atlas) category is staying true to its roots and are offering very passively safe wings with respectable and dampened reactions, which don't require precise and perfectly timed reactions. Basically, you can get away with some slop and the wing will generally recover nicely.
5. On the same tune to #4, remember, glider certification tests only test the reactions of wings, NOT the inherent passive stability/coherence of a wing. That is where actual flight reports and demo testing gliders comes in.
6. Not to play armchair pilot, but paragliding forum can offer some useful input if you know what, and what not, to look for such as biased/skewed inputs by some disgruntled and/or pessimistic/overly-optimistic pilots. At any rate, you can get a sense for a wing.
7. One last thing, there's a reason some manufactures offer prizes for the ENB category for biggest flights, such as Nova's 200K ION 2 challenge from a few years ago (low ENB category, 200 km was broken within a month or so of them offering the prize). The Atlas is very comparable to the Ion series and could be another alternative. I loved mine and it took me on nice journeys.
Anyway, sorry to drag on!
, ) jake