Well, I'm now playing with a Tokina 11-16 f2.8, it is razor sharp in the centre but a little soft at the edges unless stopped to anywhere between 5.6 to F8 then its rather good. There is a fair bit of chromatic aberration/ purple fringing but that can be sorted in Lightroom..
I need to get out and try it properly, the few shots I took yesterday evening of trees with low sun looked spectacular, the sun had the wonderful 'star' effect and almost looked surreal. I'm excited and over the holidays I'll have chance to put it through its paces to see what I really think.