Dimmable ballast vs full power

So I'm in the market for a few new lights and love the new Gavitas, particularly bc they finally run off of 120v. What I am wondering is if I should get 1000w lamps and dim them down to about 750w for most of the grow, then kick them up when flower is in full swing? Or just get the 600/750 and run them at full power the entire time? I like the idea of having the extra wattage available, but probably don't need the full 1000w for the entire time.

So the question is really, is a 1000w Gavita set at 750w equivalent to a 750w ballast running at full power? I know every manufacturer is different, and I may have to pose this question to Gavita themselves. Would the spectrum/PAR/uMol be different between the two?

Only reasons to dim other than unmanageable heat, would be to reduce coverage area or slow growth.

I dim my 600 to 400 during veg then 6oo in flower , at the end of the day if you flower for most of the cycle with a 1000 instead of a 600 your going to get near double the yield so why not ay

im doing the same as above, dimming my 600w mh to 75%. i have no choice to run a long veg time, so this cycle im giving the 75% setting a shot. after stretch my plants are 6'+ in a 6.5 tent that i managed to get another 6" height from (i mount my hoods on my ceiling joists and pull the center of the tent up an extra 6". w/o no adverse effects to the tent.