Had a play with gearing commander, http://www.gearingcommander.com/ not a lot of difference between -1 on front and +2 on back, I think +2 on back is way to go, easier to do as no hassles with sprocket nut, and less chain wear 
dropping one tooth on front is nearly exactly the same as +3 on back so +2 on back seems like a happy medium, be good to have front wheel on floor for at least some of the time 
dropping one tooth on front is nearly exactly the same as +3 on back so +2 on back seems like a happy medium, be good to have front wheel on floor for at least some of the time