Style-wise De Gea's pretty much the polar opposite of Ederson. He's a dying breed almost now though, hence not getting in the Spain squad even anymore - plus his performances have dropped off for a few seasons. I'd say he has managed to get some form back this season, but it's an area that united will be looking to improve and by getting a more proactive keeper they may be able to start playing out from the back a little.
That might weaken them a bit though, because they're built as a counter-attacking team and they'll need to adapt.
Know what you mean about it being a difficult job though. When the one shot on goal you get against you is a pretty decent chance you can end up without much chance to show what you can do and through no fault of your own. Wish we could stick with a consistent defensive line up for a while so that we might stop giving away some of the chances that are coming. We need to find some consistency soon.