Part of going with a wider bar on any given bike is going with a shorter stem as well. The two go together. Part of it has to do with the handling, which I can’t say I fully understand intellectually, but also wider bars make the cockpit feel longer, so a shorter stem makes the fit feel better.
When I started riding in the mid-late 90s my fist bike had someing like a 560mm bar with a 135mm stem.
Little by little between then and around 2012 my bars grew to 750mm and my stems were down to 40-60mm depending on the bike. I recently bumped it up to 775mm with a 60mm stem. The bike (a 2012 model) is a little short in reach by 2019 standards... I’d probably be running a 35mm stem with those same bars on a new bike.
The benefits I’ve seen ever time I go a little wider/shorter....
1- definitely less endo-prone, yet at the same time I can weight the front wheel fine when i need to.
2- It feels more controlled and stable when on the rough or going fast.
3- I feel more planted in corners. When I lean the bike over, the longer bar being dipped down pulls my weight forward and weights the front wheel.
Downsides?
1-Not as good on long stretches of road (paved, dirt or gravel)
2- once I got to 750 and beyond, I do need to pay more attention to trees in tight situations. To be honest though, it doesn’t happen very often, and in my mind having to take it a little slower past a tree now and then it’s completely worth the benefits I get the other 99% of the time.
If you are curious, I would highly encourage you to try it. It is a great update for any older bike, IMO. It is true, 700-800mm bars were originally intended for DH and FR use... but so were slack head angles and tires over 2.3”.... all of which are now common on XC and all-purpose trail bikes.