First of all thanks for all your replies. Each of them is helpful. I will try all the software mentioned (I suppose they a have trial versions I can try before buying).
Coming from a format where my widest lens, the Sigma 20mm, was giving me a fov equivalent to 32mm, I think 24mm of the 24-105 will feel very wide for a while, plus I also hope the Sigma 20mm isn't too horrible on full frame.
Having said that with so many replies mentioning stitching I must give it a try. I have tried it only once or twice in the past, and my initial feeling was I found it counterintuitive in the way I usually compose, but maybe thats something that I have to insist on to get used to 'seeing' the shot in a different way.
The other thing is how commonly I shoot in quickly changing light, and how that may mean I have to work faster.
With such competent software at putting images together so seamlessly I do appreciate how its a viable option for increased fov while avoiding the quality issues of very wide lenses. The resulting resolutions must also keep the stock agents very happy.