It is cheaper than buying Sony FS700.
Thought you might want to have a read at this.
How to best use twixtor for extreme slow motion | Philip Bloom
I got to agree with the guest writer in his blog with Twixtor's limitations. I have not much success with Twixtor either until I bought GoPro Hero 3. Still, the GoPro has its limitations.
My Failed Twixtor effects (Canon 60D, 60fps)>>>
Teachers Paintball Challenge 2012 - Cedar Primary School - YouTube
I am so happy with this smooth Twixtor (GoPro Hero 3, 120fps) >>>
My Son Stretching SlowMo - GoPro Hero 3 Black Edition - 120fps/720p - YouTube
Just thought of helping you out.