It's handy that we're comparing four 850W supplies that support 80 PLUS Gold (Corsair RMi and RMx) and Platinum (be quiet! Dark Power Pro 11 and EVGA SuperNOVA P2) certification. This is very much a high-end battle.
12V regulation is very good across a range of loads. We're seeing less than two per cent difference between best and worst results.
The cross-load focus, in the first instance, loads the supplies with 70A on the 12V line(s) and 2A on the 3.3V and 5V. Cross-load 2 turns the tables and places 12V on the two minor lines and just 2A on the meaty 12V. The purpose here is to see how well the supplies respond when lines are pushed and pulled in opposite directions.
There's very little to differentiate these supplies, all of which would be considered excellent. EVGA does as well as expected.