Save yourself the headache and don't use white marble countertop in the kitchen.

That depends. Marble is a cancerous stone and will etch when it comes into contact with acids (lemon juice, wine, tomato sauce, etc). Sealers will give you a little time to clean up spills, but you need to be very vigilant to prevent stains and etching, and even then, it's nearly impossible to keep the counter completely free from wear and tear. Choosing a honed finish can reduce the appearance of etching (which takes away the polish). Some people choose marble counter tops and are very happy with them. They know the maintenance they require, and find the end result worth the work. Other people want a lower maintenance option. For these, we suggest granite, or, if they want the look of marble, engineered quartz surfaces. There's also a new thin slab porcelain which looks like Calcutta marble which can be a nice option for some.

Yet everyone I know who bakes and/or kneads/rolls dough swears by white Carrara marble because it is the coolest surface. Any truth in that?

True, ASVInteriors, bakers seem to love it. Chocolate makers too. We actually had a customer come in today who wanted to create just a section of his counter from Carrara marble for just that, a baking space - sort of like many people do with butcher block spaces in a section of counter. This could be a great solution for a baker who doesn't want Carrara in his or her entire kitchen.

Try super white granite, more durable and it won't be as poresss.