While you wait for the experts, I remember years back many here used the boxes from Ikea but the doors from elsewhere.

There are companies that specialize in Ikea systems.

A way to get a higer end look for less.

Not all IKEA doors are the same. They have solid wood doors/fronts, and they have bargain fronts. I am not sure about slab, tho. In slab style, other materials will be much more stable. A shaker style in wood would be stable.

ETA: but the boxes are all the same and very well=made.

The cheap aprt of any csbinet is the box so what would be the point of Ikea boxes and expensive doors , I have been doing Ikea kitchens for 20+ yrs the warranty is still good and IMO the best slab doors are the high glosss ones . My last kitchen was ikea I ran catering biz often 6 people working in that kitchen , high glodd white 19 yrs not one issue still looked like new we sold last year.. Like anything else Ikea has different levels of cabinets .

Small space? what do you plan on doing w those doors? typically you want drawers !! and its hard to abuse a drawer front unless you have unruly kids or maybe dogs jumping up?? as far as wall cabinet doors… if you have ergonomic knobs or handles …are the small number of door fronts going to be abused? id go for the look you desire / since its small.. usually ikea colors and styles are varied enough.. i have a small kitchen and mid range of the ikea quality level would be fine .. its task time in the small kitchen and then exit the space. They have sturdy glides last i knew / and thats the key thing w drawers… which ought to be the focus.

Thanks for your comments everyone. I guess I just thought some of the doors were pretty lightweight when I saw them in the store and wanted some validation. I'm also considering resale value - I might want to live there for a bit and then flip it, so I don't want others to find the doors flimsy either. I appreciate all of your comments very much