I never pinch and I've never seen it affect the production of the plant overall. I mean, every indeterminate plant produces a cluster at a time every 3 leaves and continues to grow and set over the length of your season - if the plant is not setting or not growing you have a problem, and otherwise, as long as they set properly I don't see the point to compare them with a plant that was pinched! You will have a cluster less, that's all.
OTOH I have seen last year, how leaving the plants in a beer cup for (12? or more?) weeks really did stunt them.
It was a row of extra plants that were left at the farm, that didn't get put in with the others but were stuck in the ground much much later after lots of stress of all kinds - they stayed small, stopped growing after producing a few fruit in the first cluster or two, and then died a horrible death of whatever got em.
I don't know if pinching would have helped...
