Theory question for you smart guys: does taking off with trim tabs down put more or less stress on drive, or is it negligible?
27’ /single/ v-bottom
No problem planing, just wondered.

Theoretically speaking, the further you drop your tabs, the more drag you create for the hull. That said, you would put a very slightly greater load on your drive. I wouldn't worry about it at all.

In my head it made sense that more tab = more leverage= more load. Just wondering. Thanks

A little more in theory, but no big deal.

Negligible.
The weak link on a Bravo drive is upper case flex and gear friction with input torque over 450 ft lbs.
If tabs (2/3 down) allow you to get promptly onto plane with less throttle than zero tabs (full up) , then keeping input torque under 350 ft lbs will greatly extend the happy life of your Bravo drive.
Things like U-joints depend more on the drive angle. Neutral trim is easier on U joints than extreme up or extreme down trim angles (but U joints on a Bravo rarely are a failure point when you replace them every 150 hours.
Heat is also a drive killer. Drive showers do help.

Think of it this way: when you put the tabs down, does the boat slow down? If so you are putting more stress on everything. A small speed lose shouldn't be an issue though.

I almost always use the tabs to get on plane on twin engine boats.
The boat gets up on plane quicker.
On boats that pitch the bow up when planing, it keeps your field of vision much better.
That's the point when you are climbing through the RPMs and throwing the most torque at the gear sets. The sooner you get through that "period", the better.