We moved our boys in together at about 3.5 and 6 and did a lofted bed setup to maximize the available floor space in their room (not especially large, mid-century house). We did a lower stair bed for older DS where the stairs double as drawers, and the other pillar of the loft provides bookshelves. It's taller than the Kura, but not quite as high as some bunks. We also made sure the mattress was on the thinner side to make sure the edge rails provide maximum fall out protection. He's 3 years into it now and has never fallen out or down the stairs.
We then got a twin platform bed with storage drawer underneath for younger DS that we tuck under the loft at the head. It's a good setup and leaves as much space as we can for toys and play area.
What we bought was a little more expensive than Ikea, but not high-end furniture - still assemble it yourself.

I prefer 2 twin beds if you have the room. Headboards are okay, but no foot boards.

Don't get throwaway furniture. Get something your kids will use now and also for years to come.
Get creative with toy storage and room layout.

My kids used the kura together for one year, and then one used it as his own bed and we got a regular twin bed for ods, even while they were sharing a room.

We later switched to dedicated bunk beds and they used those for two years, and that was the end of them sharing a room.

I would not get a kura and I would not get bunk beds, if the room is big. I would consider getting twin beds that can be separate or stacked for that flexibility. I wish I would have done that from the beginning.

OP here- I found some old threads about the KURA which were helpful!

Moving to a new house and my boys, ages 3 and 5, will be sharing a room and it will be the main “play” room as well. It’s a large room but I’m wondering the beds to get. Right now, DS1 currently sleeps in a full bed and DS2 is in his crib with the side removed. I don’t think I want a normal sized bunk bed (DS1 fell off one this summer at a beach house...) but thinking about the IKEA KURA loft bed that you see everywhere. Or do I just get 2 full size beds so I don’t have to buy new ones in a few years?

For people that have the KURA bed, how long did your kid(s) use it? It would first be used as a bunk bed with a mattress on the floor for DS1.