Despite the constant (and I do mean constant) outages on the test server, I've managed to do a bit of testing on the new mining changes. The biggest thing I've identified is the "proximity" nerf. Basically this means that you must stand within 1-2 feet of the node in order to mine it. No more standing at max range to avoid mobs, you're going to have to be on top of the thing. To my mind this is the biggie - the most significant change that was made.
I went to the arakkoa camp south of Allerian Stronghold, which has level 64-65 mobs. There were two nodes in this area with mobs in the vicinity. The first one I mined with a mob standing roughly 10-15 feet away, he didn't aggro on me. This is what I would expect being a level 70. The next one I mined was about the same situation and I did not have trouble with it.
Next I went to Skettis, the level 70 arakkoa camp in the Skethyl Mountains. This area should be tough for me to mine, if the aggro has been modified. I located 3-4 nodes in here, including one that was at the edge of the camp. Once again mobs were within 10-20 feet of me, yet I did not pull aggro even once. Well actually, that's not entirely true. A water elemental did jump me one time when he pathed closer to me while I was still mining. But he came pretty close to me, within a range that I would expect to draw aggro anyway. So from what I can see, world aggro has not been modified. At least not based on my experiences in Terokkar Forest. I didn't test every zone and I'm not sure I feel a need to be that thorough :P
My next test was stealth mining... yes yes I realize this doesn't affect most of you. But since it's my bread and butter (ore and motes?) I was sweating over it. Especially after my world test produced no detectable change, I was even more concerned that they nerfed my precious dungeon mining. I made about 5-6 passs through the Mana Tombs and the good news? Minimal nerfing here. The biggest change is just the proximity thing. Since I can't stand 10 feet from the node anymore, I'm closer to mobs who will want to pounce on me. There are several spawns in Mana Tombs where those few feet make the difference between a minable node and an inaccessible one.
I also suspect that they did increase the aggro a bit, that's really hard to quantify though. If you're familiar with the Mana Tombs, you know that the first spawn is in the corridor rooms after the Crescent Hall. If the ore spawns in an alcove, you're safe. If the ore spawns inside the first room on a rock slope, you're also safe. But the ore in the second room, I was unable to get. I even tried sapping the closest mob and his buddies still jumped me. This is part of why I think the aggro may have been tweaked a bit, because I think I should have been far enough from them that I would normally have been able to mine those nodes without a problem. But I tried three times and I couldn't get it with the new rules.
You would think that this would also create problems with the second spawn - in Shaffar's room. Strangely it did not, the floor node by Shaffar was fine. I got it with no aggro, perhaps because the mobs were facing away from me. The one up the slope is also fine, no mobs are terribly close to it. Now the floor node closest to the entry door is definitely an issue, those pathers go right by it. Since I can no longer stand at the far end of the pit to mine it, I'm definitely in their range. I found a trick though =) You can sap one of them when they path over to Shaffar. They both stop until the sap wears off, then you zip over to the node and grab the ore. Cake!
Overall, I think Mana Tombs is minimally affected by this change. It only causes problems for 2 of the 9 possible locations of the first node and none of the locations for the second node. So I think it's worth keeping in the rotation. The only major problem I can see is for those who are under level 70, I think the proximity change will likely hurt those folks.
As for world mining, I think this was probably minimally impacted as well. I will continue checking a few more areas but for the most part I don't think anyone is going to be hugely harmed by the change.