The current studio display is 5k native but renders at 2560x1440
No, it doesn't.
The Studio Display renders at 5k. The misleading "(looks like) 2560x1440" description in display settings effectively means that the
UI size - system fonts, menus, buttons etc. are double-size so they render
physically the same height/width as you'd get on an old 27" 1440p display. Unless you're running ancient pre-retina software, though, it will be rendered with twice as many pixels in each direction and contain
far more detail.
almost has me wanting to get one of those 5K X 1440 displays since its about the same res visually.
No, it isn't. (see above).
Even if you choose a different scaled mode to get a different-sized UI, everything is rendered at
twice the stated resolution and downsampled to fit whatever display you have (whether it is 5k or 4k) and contains far more detail than you would see on a display with that
actual resolution. Even on a 4k display in scaled "looks like 2560x1440" mode you get 5k downsampled to 4k which has far more detail than 2560x1440 pixels could show.
These posts show why apple really, really needs to stop confusing scaling with resolution by describing 5k with 2:1 scaling as "2560x1440" because it simply
isn't 2550x1440 pixels. Instead, they've removed the "looks like" prefix to make it
even more misleading. You can kinda defend the logic if you're a programmer working out how to scale screen coordinates - but from a user POV it's nonsense.