The standard legs are adjustable to account for floor deflection. I don't see the problem. Any item that generates enough heat to affect the legs is too hot to be placed under the wood cabinets.

They are made to work with their plinths what is your issue your vent would be in front of the plinth

Our contractor built a base for our IKEA cabinets. It voids the warranty, but I expect never to need it given the particulars of our install. YMMV.

Hi JY - those legs are not intended to be visible and like others here mention, each is adjustable which allows you to level the base cabinets so that they can evenly support the weight of countertops. They're covered by the toe kicks that adhere to them with plastic clips. This video shows how someone built radiator covers into IKEA toekicks:

https://www.youtube.com/watch?v=WyZTK0-7wAE

The sektion plastic legs are custom made to push into predrilled holes on bottom of sektion base cabinets without screws or fasteners. There is a custom clip which works with Ikea’s toe kick boards (slides in). The capita legs can be used but need to have holes drilled in the cabinet and do not have the custom clips. The capita legs would be just like any other adjustable legs in the same height range. The biggest capita plus is they are steel and when screwed in and adjusted are strong. Since the sektion cabinets depend mostly on the suspension rail for support, the sektion plastic legs are adequate to task of leveling the cabinets (uneven floors). If you want to put a toe kick then you’ll need to figure out something on your own if you used the capita legs. Personally leaving the under cabinet area open would be a different look that some may like. Also, haven’t tested it but I would trust the capita steel legs over the sektion plastic leg if somebody decided get up and sit or stand on the edge of the counter. Just saying

I am curious if anyone has done the metal legs (for the look) and then left them uncovered by toe kicks.

we used the capita legs and left them uncovered.

we used the capita legs and left them uncovered. matches brushed nickle hardware nicely. not a great photo due to sun streaming in above the vanity.

I want to use exposed capita legs under my kitchen cabinets which means I'll have to do my floor first and under the cabinets. I am still exploring different flooring. But since it will be under the weight of the cabinets/countertop and stuff, do you think I could use something like Forbo Marmoleum?