I know this is an older thread, but since it was recently revived, I thought I'd add my $0.02. I've found that the RPM shown when flying toward or away from the home point is a crude, but effective way of judging the wind load.
If you're in sport mode, and find yourself going 40+ MPH in a given direction, take note of the RPM. If it's between 6-8k, chances are you have a strong tailwind. In NO WIND, the 40 MPH speed will typically run between 8-8.5k - so if it's cruising without load on the props, be prepared for a slog coming home. If at any point you see 9-9.5k on the props you know she's giving it all she's got and won't be able to go any faster than the current speed.
I always look at the RPM during the first 1000' feet going away from the HP. If I see anything more than 8k, I stop, and return to the HP to gauge the RPM. You'll get a pretty good feel for which direction creates the largest load, and can make better/safer use of your battery.