I tried it today on my 33 gtst, was a little hard to start first go, and then hunted around for a while before it idled. It has since been rock solid and starts perfectly. In terms of performance it feels quite responsive, especially throughout the midrange, but I could never be certain without chucking it on a dyno.
I wasn't too concerned about running lean as I have a rom tune that is rich with advanced timing... (I couldn't hear any pinging today) but I do believe it leaned the ratios a little as I am now sans most of the crackles and pops that come from the exhaust.
I also found it quite amusing that there was a shell rep waiting at the bowsers, handing out brochures for OE100 to everyone, and telling them that this "wonderful new fuel will clean their fuel systems"