Jeff,
Im not sure what variety you are growing or where you're growing them,
but if you don't have good internodal spacing then I would shoot thin.
Shoot thinning, IMHO, opens up the canopy allowing more air flow and
more sunlight into the developing basal buds where next years shoots
will grow from. If your internodal spacings are close, then thinning
shoots will help balance the canopy and give the vine a chance to have
better spacing next season. If your spacings are good then I would
imagine you have enough buds on the canes laid down that non fruiting
shoots wont be a drain so much as a help when it comes to ripening the
fruit.
It would be interesting to know what crop weight you were aiming for as
well. It has been my experience that this early in the season, or
rather your season as I live in NZ, that the vines will have more than
enough time and energy to put up more canopy if they feel the need.