According to the Barista Hustle advanced espresso course, the advantages of lower pressure are reduction in the likelihood of channelling and choking, but this comes at the expense of maximising extraction.
Increasing pressure increases flow and thus extraction, up to a point (where it can cause channeling or compact the puck to the point that it increases resistance and reduces the extraction).
From playing around with pressure profiling I agree with @Doram. The lever profile does a good job of managing how the resistance of the puck changes during a brew.
For a fixed pressure machine, the advice from the Barista Hustle course was to brew at the highest pressure that was still giving good consistent shots. This maximises extraction, and the perceived wisdom seems to be that for any particular brewing method maximising extraction tends to correlate with better flavour.
There’s no perfect point for any of this espresso game though. There are lots of variables, and most of them will change how the espresso tastes, but whether that is a good or bad change depends on the coffee and your personal preferences.
Assuming you’re doing mostly medium to dark roasts (ie not Nordic light super acidic roasts), then I’d stick with the standard 9 bar shot, and 1:2 ratio (coffee:espresso). If you can do this consistently, and have perfected how to dial in and prep the puck, then I would play with different ratios. Only once you’ve mastered all of that would I bother playing with pressure. If you don’t master the fundamentals first then you risk getting lost in the number of variables available, and probably won’t have developed a discerning enough palette to tell the impact anyway.
Enjoy it, espresso making is a journey, not a destination