I'm interested in this lens, and I've searched out every pre-release review I could find. Most early reviewers of course note they are working with an early pre-release model. One thing I'm a bit worried about is that some of the posted pictures don't seem very sharp. Some pictures do. I suppose it could be a combination of having a pre-release lens and different photographers getting used to the lens?
I own both the 1.4X & 2.0X teleconverters, so between the relatively low price of the lens it seems like a "no brainer" to purchase one. But, I'm worried that it might be too out classed by my 50-140mm (with our without teleconverters). If I could afford the Red Badge 100-400mm I'd probably go for that.
In the end I'll keep my eye out for reviews of production models, and see what the latest reviewers say about this lens. If anyone out there gets their hands on one please share your experience and insight, and of course pics! I trust this group!