Oh, certainly. The live feedback will still give you information as to whether a change in body position you make is better or worse. Looking at the data post-jump will also give you a sense of what worked well and what didn't. It's just that the specific numbers themselves won't be reliable, especially if your pattern involves one or two turns. And comparing those numbers across different days / wind conditions would hold even less value.
I realize this thread is old, but thought I would chime in anyhow. It seems like taking FlySight data without accounting for wind is *almost* worthless. With strong uppers you could easily see a swing of around +/- .4 G/R. Quite possible OP was already adjusting for wind, but it seems like a must know for anyone trying to hone in their tracking suit performance and I haven't really seen much on this topic in the forums. Link on how to adjust for wind with the FlySight viewer: