Which Groupset?

No.

Considering most races come down to a sprint. I'd put money on the cyclist with a heavy groupset that shifted into the correct gear, without need to reduce pedal pressure, over the one with the flaky 1900g groupset anyday.

TBH its even the same climbing. A few grams saved wont compete with being able to pop inand out of the saddle, adjusting gears accordingly. Again still with the pedals fully weighted.

It's not even that specific - doesn't need to be a sprint. Drop a chain on a climb with your feeble but light groupset (I'm looking at you SRAM) and you lose the Tour.