Is a Multi-site setup work for universal carts?

I am working on creating two more sites for a client in addition to the one they already have. I decided I want to take a multi-brand approach similar to 1800flowers.com in how they allow their customers to shop across their family of brands with one shopping cart. Depending on the site you land is how the domains are used for instance 1800flowers.com/fanniemay or fanniwmay.com/1800flowers, either way they have separate domains but can host each other sites but more importantly, add products across each brand in one checkout process.

All this being said is a multisite feature the way to go?

I’ve done some reading up on this but I’d like to hear other developers experiences.