The information available to play this game is - as of 5th October your grapes are ripe enough to pick. They would produce a wine of around 9-9.5 % alcohol which is plenty and would make a nice wine but you'd probably need a tiny amount of sugar added to the tank to bring it up to 10%. The key thing isn't this but, it's ( adopts Greg Wallace from Masterchef voice) flavour. They are already picking up some nice interesting qualities beyond just tasting of sugar and acid but, if you left them for another week, they could get really interesting. So, it seems obvious that you'd leave them. The dilemma is, the weather is currently perfect but, next week there's a chance of rain which adds the risk of disease and would dilute the juice. Here's the Met Office forecast.
UK Outlook for Sunday 9 Oct 2016 to Tuesday 18 Oct 2016: The largely settled weather is expected to continue through much of this period. Despite some spells of bright or sunny intervals, it will often be rather cloudy with outbreaks of light rain in places, especially across eastern coasts. It will remain rather cold for the time of year with breezy conditions continuing, especially across more coastal areas. There will also be some cold nights as well with a local frost possible and the chance of some mist or fog patches. Stronger winds and more in the way of rainfall may affect western areas towards the latter part of this period, bringing a return to milder weather, but detail remains uncertain about this change of weather type with the potential for the largely dry conditions persisting throughout.
"Stronger Winds and more in the way of rain may affect Western areas". Accuweather has at least some rain 15th -17th October which is when we would pick.
What do you do, Twist or Stick? Answers on a postcard please.