I haven't posted this yet but Prusa has a branch of Slic3r - called the Prusa Edition - on their web site. It is remarkably better than stock Slic3r and has some really excellent new features AND Prusa's commitment to migrate the code over to C++ for performance and stability. I've used it quite a lot the last few weeks and continue to be impressed with how much better it is over the stock Slic3r.
This is a great lead!  
I've been playing around with the Prusa version of Slic3r for the last few days, and I have to say that I really, really like it.  I'm still testing, but I find that I am getting really good results with everything I've thrown at it so far - as good or better than Cura and S3D in my experience.
The UI is better than any slicer that I've used; the breakdown of settings between Print/Printer/filament is really flexible, clean and intuitive.  It also lends itself to experimentation (by easily maintaining multiple sets/versions of discrete settings and the ability to add notes along with them).  
If your like me, and basically dismissed Slic3r in the past - you might want to take a look at this new version...  It's pretty slick.