Hi steelwindmachine,
Thanks for the picture. You’d certainly want to take a look at that in person, as I’m not seeing that described on the web site, but I don’t have an Ikea where I can go to confirm. Perhaps that is something you could report back on if you do go visit and look in person.
There is an older post that has a few good links here about appropriate foundations, here and here.
Using 1" x 4" (as you know, this is really .75" thick by about 3.5" wide) with a center support (a good grade of wood – poplar is popular), is a common strong arrangement, with 3" or less for the gaps, for a solid latex mattress. The boards in your photo look to be more like 1" x 6". Just check the gaps and the strength of the wood if you find one of these on display.
I’ll be interested in what you find should you have a chance to visit your local Ikea store.
Phoenix