Would .41 g of Marijuana be considered usable? Would anyone try a case to a jury with this amount?

Have we tried that amount here? Yes.

Have we gotten a conviction on that amount here? Yes, but it was a long time ago.

Honestly, the weight itself can be very deceiving and it really depends on visual inspect of the marijuana. I've seen marijuana the < 1 gram range that was obviously unusable from looking at it and some that would definitely make for a solid joint.

The jury isn't going to care about the number of the weight as much as what it looks like in the bag, from my experience.

As a general rule now, I'm not going to try burn a jury on a case with less than half a gram unless there is a compelling reason otherwise, but that's more about case management economy than anything.