Based on the timings above the legendary / time is even between mp7 and mp3. If you have max mf, mp7 is around a 3.5% more 6 affix chance than mp3. MP3 is 30% more rares / time on mp3 which works out to a 26% more 6 affix / time. So mp3 is the winner. http://www.diablofans.com/topic/57939-magic-find-and-its-efficiency-a-statistical-insight/
"I only pick i63 armour, jewellery and 1h weapons anywa"
I pickup 58 armor pieces, only difference is base armor in mp1+.
MP3 alkaizer run + keep3 partial can be done in ~15mins:
I'm not following. 450 MF gives a drop rate of x * (1 + 450/100). 550 MF gives a drop rate of x * (1 + 550/100). This is an increase (1 +550/100)/(1 + 450/100) = 18.2% and remains constant regardless of the base drop rate, x. It applies just as well to 6-affix rares as it does to legendaries. Where do you get 3.5%?
Things to consider:
Concerning Extra drop:
White mobs have a base 30% chance to drop. If they pass that they have a 33% chance to drop an item. So mp5 is 2x whites drops but for a ~4x more hp to burn away (for loot/hp to be equal mf would have to 2x between mp1 and mp5). So mp10 gives x4 whites drops for a ~22 more hp to burn away (for loot/hp to be equal mf would need be 5.5x greater in mp10 then 1). Now higher mp starts becoming good when you have a dps level that compensates for this.
On mp1 you have 400mf (11.50)
On mp10 you have 625mf ~(12.3625) +7.5% I think this is more around +6.5% because the act 3 alkaizer focus's on whites compared to act 1, 2 runs and thus does not benefit affix buff on the guaranteed drop.
MF %6A %5A %4A
0 10.28 30.52 59.21
250 11.02 31.89 57.09
400 11.50 32.78 55.72
1000 13.80 36.84 49.36
The effect that MF has on increasing the number of possible affixes on rare items appears to be minimal and close to neglible for the standard elite drops. It does, however, appear to have a prominent effect on the NV rare drop.
I usually simplify the problem into: each mp = 40% more hp, 20% more legendary, 10% more rare.