Gas and Electric supplier - fix now to 2014 or variable?

[Welshbeef]

Well I've been with E-On for the last 7 odd years great overall service ad keen pricing.

Anyway current fixed deal ends today sadly...
So looking at the new offerings and the best variable rate E-on do will be £100 more per year and the fixed until apr 2014 is £126 more per year. (incl clubcard points)

However us witch shows that the best fixed deal up to feb2014 is Scottish power which would be only £70 more but clearly no clubcard points.
Cheapest variable supplier is via sainsburys energy with is £25 more per year

So two questions is it worth fixing? If so is Scottish worth the switch?
If variable is Sainsburys a good supplier?

I'm a loyal customer and respect good service but with the disparity in prices it does make you think I could get one tank of fuel out of them for the same.