In a vaguely related manner (actually because I can't find the right thread....) We were talking about running lean for improved economy.
As I said, I've not tried it, but I'm slowly working my way through 'Introduction to Internal Combustion Engines' by R Stone. In there he states that maximum power is acieved at approx 10% rich or stoichiometric, and maximum economy at approx 10%lean of stoic.
The theory goes that if the throttle is fixed, torque will increase and decrease respectively, but in the case of lean running, the idea is that you open the throttle more to achieve the desired torque, and the reduction in efficiency due to being lean is more than compensted by the improvment in efficiency due to the reduced pumping losses. Obviously as load increases this tradeoff becomes less and less, so you can move smoothly back towards lambda 1 and richer as you get towards the WOT load.
So, the implication is that you should run you cruise loads sites at around lambda 1.1, assuming your engine can tolerate it, for best economy. However, I would still want to be sure I had a pretty good transient fuelling setup to avoid any stumbles as you tip in.