My argument in regards to save percentage is that save percentage is reflective of the team you play for. The better defensive team you have, the better save percentage you will have. Look at Ben Scrivens in LA versus Ben Scrivens in Edmonton. You put any goalie on a solid defensive team and his save percentage will increase, you put them on a terrible team that plays wide open hockey and allows a lot of breakaways/open men in front of the net, and the save percentage will drop.
The short answer to Ben Scrivens is that any goaltender can put up an elite or an awful save percentage in a small sample size. For every goaltender you can name who saw an increase in sv% going to a stronger team, I can probably name a goalie whose sv% dropped after going to a better team.
Luongo played for Florida for 5 full seasons, while Florida finished 27th, 28th, 28th, 24th, and 21st. 5v5 sv%: 0.9295.
He then played for Vancouver for 7.5 seasons, while the Canucks finished 8th, 21st, 7th, 5th, 1st, 1st, and 8th. 5v5 sv%: 0.9284.
If you apply the save percentage he achieved in Florida and apply it to the quantity of shots he faced in Vancouver, the difference is ~11 goals over 448 games, or roughly 1-2 goals per year.
The difference in sv% from Luongo of Tire Fire Florida and Luongo of back to back Pres trophy Vancouver is worth 1-2 goals per year.
Over the long run (3000+ shots faced), there is no real difference to shot quality between teams. Yes, in Edmonton or Buffalo, there are probably going to be more 5 alarm scoring chances against, but there's also going to be proportionately more 'easy' saves too. There's been a lot of research on this.