RESULTS WILL VARY
What I did was take a couple videos...one of me farming MP10, one of MP7. I selected MP10 because it is the highest MP available and also, in turn, the one that is being given the most XP boost with the next patch. I chose MP 7 because it is where I feel I am still able to kill trash mobs and elite's at a good speed, maintain WoTB, and I also have enough defense to survive when I take War Cry out of my build and put in Rend, which is my preferred farming build. Both video's were shot in the Keep Depths lvl 2, because that is my preferred farming area. No increase xp% items were used during the runs, but elite kills did contribute to neph valor stacks at different rates and different times throughout the run (although my idea was to get an approximation, not an exact science here) For the purpose of simplicity I will be calculating XP rate with 0 stacks and 5 stacks of N.V. for the MP levels. Also, I will be using my xp/min number as the base 0 N.V. number in the calculations....I know this creates some discrepencies, but it will give a rough idea.
Now, to clarify, I am not trying to find my optimum MP level with these vids, they are a very small sample, and you can witness in the MP10 video I did end up having to backtrack a ways, and it did not appear to have the same monster density....but rather I am trying to see if high level WW barbs will see a significant benefit post-patch with regards to running a higher MP with their best gear, as opposed to throttling damage, stacking XP % items, and running on a lower MP.
The given that I am working with is that I have timed my MP0 runs in the past and have come to the conclusion that with stacking increase xp% items and throttling my damage the best I was able to get on a single run was 1.5 mill xp per minute. After I accounted for lost time restarting games and travel distance and RNG of maps I was coming out to about 65-85 mill XP per hour.
The benefits with running a higher MP will be less restarting of the individual games, more (and better quality) loot, less travel time because the mobs will now take longer to kill individually, and a higher chance for 1.07 crafting items (as outlined in the patch notes).
Currently MP7 gives 95% increase to XP, this will become 275% after patch 1.07 if the numbers remain the same. With 5 stacks of NV this will cap out at 350% XP.
For this current run I gained 2,612,762 XP in 3 minutes or 870,920 XP per minute
0 N.V. stacks = 195% XP from every mob
5 N.V. stacks = 270% XP from every mob
0 N.V. stacks = 375% XP from every mob
5 N.V. stacks = 450% XP from every mob
That means in order to estimate what 1.07 figures will look like I need to multiply:
(current XP per min from 1.06) * (XP % for 1.07 / XP % for 1.06 <0 N.V. stack>)
In order to calculate 5 stacks of N.V. for 1.06 the figures will come from this formula:
(current XP per min from 1.06) * (XP % for 1.06 <5 N.V. stack> / XP % for 1.06 <0 N.V. stack>)
All calculations will be done with this method....I hate showing my work...makes me feel like someone is going to find a glaring hole in it.....which I hope won't happen, but....I am not the perfect mathematician.
MP10 will be substituted with an average of 581,500 XP per min in 1.06 with 0 N.V. as I have calculated from the video and 510% XP, up from 160% boost as indicated in the patch notes, I don't want to type it all out again, so let me know if you are confused where it all came from.
MP10 video: http://www.youtube.com/watch?v=txBLzBA4bUw&feature=youtu.be
1.06 0 stack N.V. - 870,920 xp/min
1.06 5 stack N.V. - 1,205,889 xp/min
1.07 (proposed) 0 stack N.V. - 1,674,846 xp/min
1.07 (proposed) 5 stack N.V. - 2,009,815 xp/min
1.06 0 stack N.V. - 581,500 xp/min
1.06 5 stack N.V. - 854,078 xp/min
1.07 (proposed) 0 stack N.V. - 1,853,531 xp/min
1.07 (proposed) 5 stack N.V. - 2,126,109 xp/min
As you can see these values are significantly higher then they are in 1.06, and even clear my best throttled damage + xp% times that I have been able to pull off at 1.5 mill xp/min. Obviously +xp% items will have to be factored in and will have a larger impact on reduced MP's but just for a generous estimate I think we can safely assume if these number hold true higher level WW barbs that are capable of upper MP farming will be able to level 30%+ faster in higher MP's without even using XP% items, get better quality drops, and be able to keep WoTB up a lot easier.