On Thursday, January 23, 2020 at 12:53:35 PM UTC-8, wrote:
I have not seen a better airmass vario system than the Butterfly. Most importantly to me, its wind solutions are amazingly good. It has been a game-changer for many in the Tehachapi-Southern Sierra tribe. The location of convergence lines is critical to X-C in the Owens Valley and Great Basin. The accuracy and update rate of Butterfly winds are outstanding and a tremendous asset it "convergence hunting. My only issue is its complexity, i.e., the large number of user-defined parameters available and what exactly their effects are on vario display, sensitivity and response. I have flown a Butterfly for 3 years, incrementally changing some parameters and am still not comfortable with its behaviors, especially when compared to the CAI 302.

It terms of "best" vario for X-C flying, the 302 is also very good and an incredible value.

No just for convergence: I been able to find weak waves on days when it was very difficult by watching the sudden increase in headwind. I will see an increase of 5 - 10 knots and sure enough there it is. Also have found persistent exploitable afternoon Zephyrs in the Minden area. Never have seen these on the more traditional wind calcs.

Paired with iGlide, you will get a wind vector calculated each second and displayed in the lift dot of the thermal assistant. The wind vectors reliably point towards the center of the lift. I've been told this may be unique to rough/strong western thermals, but it works well there in strong but very inconsistent (and therefore hard to center) lift.