I think the synopsis is that bar width is a compromise between comfort and control. You might take the advice to optimize your weakness, but I don’t think everyone will agree with that. Personally, that’s my choice though - on a bell curve I’m a stronger climber than descender so I default to a slightly wider bar. I’ve landed on 770, or 780 depending on the bike. I also think that most people can adapt to different width bars quicker than expected.
You have an opportunity to try wider bars than you’re used to, why not use that? If you do decide to cut them, go 5mm increments (on each side so a total of 1cm per cut) - pipe cutter is OK if you have aluminum bars, but it’s very possible to cut bars on the bike with a cutting guide and proper hack saw.