I just cut through a 6x6 pressure treated beam with my Ryobi brushless circular saw. Didn’t even bother to upgrade to a diablo blade. And it worked great!
I made six more similar cuts. No problem.
If I was doing this every day, would I upgrade to Milwaukee? Probably. (More than likely buy a corded saw.) But for weekend home improvement projects, don’t doubt the power!
They are famtastic, and used prices on eBay moved them into my budget.
My most recent project was fencing about 5.5 acres in, about 500ft of the fence line was on a rock shelf. tposts have a hard time being drove by hand into boulders. I used a 1" x 18" bit to drill all but two of the posts on that side.