I've been knocking around Israel this week with a new 3X4' Sunbounce reflector. I find it works as advertised, and for running and gunning, is far superior to anything I've used before. My Israeli grip fell in love with this tool. Setup takes about 30 seconds, and although I haven't mounted it on a stand yet, it should be much easier to mount with the hard points on the frame.
Flexfills still have a place in my kit, but I will always reach for these first if time and circumstances allow. I plan to add the silver/gold striped material...it should be the perfect amount of warmth over the full silver or gold I have now. The only downside...it's too long to stuff into my tripod case, so I had to gate check it.