Always used Momentum99, Shell is quite a bit dearer and I don't experience any difference.
On the topic of pump fuel, why do we not get E85 over here? Been reading a lot of stuff out of Aus about SR tuning and E85 is very popular there. They are making way more power on corn juice over 98 unleaded, it's almost unbelievable.
I'm sure that Morrison's used to sell it in 2007/8. I noticed in San Antonio, Texas today that E85 is the same price as 91 AKI. Apparently you use a lot more of the stuff, but as you say, the performance benefits are huge.