I only have my low level bow scout so I can't test fully, but I did some tests with bl0b earlier this weekend, and this is what we got so far.
-Ice and fire stack their new effects properly, but wind doesn't. Already mentioned it in a thread in pegasus somewhere.
-Even though ice and fire stack their effects properly, we felt they just weren't worth it. The rather low rate of success means you have to be spamming these skills to keep their effect up properly, making it nigh impossible to actually use your other skills. Fire just needs a slightly higher success rate, since the wounded effect makes it a niche skill that is OK to use in its niche (preventing stalemates from healing too much), but ice needs some work. Why would you use ice? For increased (crit) damage, pretty obviously. But to keep this effect up, you have to spam ice arrows, which is a low skill power skill. So in the end you don't really do any extra damage, you might actually do lower damage due to not having time for using your other, stronger skills.
Ice arrow should be changed, you can either buff its success rate to make it more reliable, or make it give another effect than critical impact. I personally thought ice arrow should have a 50-60% chance of boosting crit damage by the full 50% crit damage for 3 seconds. Like that you can ice arrow>impact arrow or ice arrow>phoenix/entangling and gamble on a crit. Would greatly augment burst damage and make it less needed to be spamming the arrows to get actual effect out of it.