Canon 70-200 f4L vs Sigma 70-200 f2.8 OS

[Rexxar]

I'm looking at selling my Canon 70-200 f 4 L (Non-IS) , and replacing it with the Sigma 70-200 f 2.8

Has anyone had both (or similar comparing apertures) ? Weighing up whether the lower aperture is worth it , or if i'd be better off going for a longer non-stabilized lens (As often shoot from tripod) Wanting something that's decent when going to wildlife parks or zoos as well as wildlife photography when out and about...

What say the photographers of OCUK?

 

[Rexxar]

@GMac11 Appreciate that write up , Keeping the f4 L non-IS and getting a 1.4x tc might be a good shout, and cheaper too. I'll experiment bumping the ISO up a bit and see if that changes my mind at all... Hadn't even thought of weight , Shooting with an 80D which seems good enough for my needs at the moment.