I did the power-leveling trick with the Brotherhood of Steel patrol missions. I did it for a few hours (got bored...it gets boring).
Leveled up to level 80 or 81 using this trick. You can farm around 20k XP an hour with the method. It's legit. It is not an exploit. You have to be sneaky enough to kill the patrol person, out of sight, or you'll enrage the entire BoS! But once you figure out where to trick the patrol guy to follow you, then it is easy to sneakily kill him.
Max out your intelligence so that your XP rewards are the highest. I probably did the patrol mission hundreds of times before I stopped. Loot the patrol dudes' bodies, as well.
It is not game-breaking. I maxed out my SPECIAL stats and maxed out some obvious ones (like armoror and gun smith). But, still, the majority of perks are still not unlocked. I've got a loooong way to go to unlock the rest of the perks.
I agree that use Danse is the best companion.
But I prefer having no companions because they judge me and dislike things I do. The bad guys hate it when I do good, the good guys hate it when I do sneaky things.
Even though I'm level 80 or 81, I still got killed by a suicider super mutant. I had less than half health, though. So leveling up doesn't make you super powerful, just allows you to invest in more perks. If you're willing to spend the time repeating the same damn missions over and over, do it.