Sam
I went through exactly this dilemma when speccing up my March 09 bike.
In short - go for the enduro box.
The enduro box only changes 1st gear, and reduces it by about 10%. I live and work in London and the difference is incredible compared to the standard box. I can filter at slow speed more smoothly and with the clutch out for significantly longer. Low speed manouevering is so much easier and less jerky (u turns, riding slower with clutch out etc).
Sure the gap between 1st and 2nd is a bit bigger but not so big that you notice it. Like any vehicle, you get used to it.
If you are planning on doing some off road, its essential. I'd argue that for town riding its essential too.
Some of this parish reckon that even the enduro box 1st gear is still a bit too high for off road use.
This is my 3rd 1200GS, and the first 2 had the standard box. I wish I'd realised the benefits of the enduro box earlier. The salesmen are generally crap, have never ridden a 1200 with an enduro box and talk a lot of made up shite about it.
Happy to talk more if you want - PM me.
Mike.