Not sure if I'll bother this year. Enjoyed it first time as was with a decent chatty group. Last year I set off in the first group at 7am, but the group I ended up with were a miserable bunch (first on the road) and one or two of the guys were seriously quick, and wanted to set the pace - it got a bit insane, and a few of them nearly ended up under a BMW taking a bend without looking. Ended up spending about 50 miles on my todd.
Best advice, don't go off at 7am - maybe go for 7:15 or 7:30, then you'll be able to pick and mix the groups depending upon your pace.