I know I'm late to the party, and I've had some very good experiences with them.
I've also seen beyond the 'glow' they seem to have for many.
120 TSX - 200 yard caribou, 7mm-08
235 TSX (#2)- 150 yard moose, 375-350 Rem Mag
100 XFB - 200 yards caribou x2, 7mm-08
225 XFB - 125 yards caribou, 340 Weatherby
85 XBT - 300-400 yards caribou, 6mm
225 XFB - 495 meters moose, 340 Weatherby
Most have zipped through, most have been effective quite quickly. But copper is always going to be hard. Sometimes it just doesn't open as well and penetrate as well as we hope.