A lot of good ideas, technical goodies etc., but I'd go with Wileys arguments. However, I proposed another approach as to how to proceed, and I still stick to my arguments.
1. Any action done alone needs to be confirmed by the fellow crew member(s). So why do it in the first place? To eliminate error? To crosscheck? I do not believe that such procedures are superior in trapping errors, as BOTH individualists might make errors, eventually doubling the risk. We are a team after all, aren't we?
2. Anything done in advance is by definition imprecise, as not all values are yet known. So why do it then? To give us a preliminary picture? To raise awareness? I do not believe that this helps trapping errors. I believe it might even set a trap, as it preconceives our thinking. It might lead to the feeling " ... it has already been covered".
As a consequence to these two arguments, I prefer working as follows:
Do all the math on the flightplan, as usual. We can crosscheck that, to raise awareness, big picture. Wait for the TO calculations until receipt of the loadsheet. Then go through it TOGETHER. Note the values on the flpl. Go into the laptop/EFB/charts, with the ACTUAL VALUES. Once the result shows, insert the necessary values into the FMC, set the MCP/FCP. All this done TOGETHER, do a quick CROSSCHECK a): loadsheet vs. FMC (grossweight), and a second crosscheck b): FMC vs. laptop/EFB/chart (greendot/Vref30).
This should take no more than three minutes, during which the crew may throw everybody out of the cockpit. Additionally such a procedure can be applied with anything from two to one laptops/EFBs, any kind of charts and even a precalculated ACARS from dispatch.
KISS