Novelty is interesting. The domme already has a harem, adding one more sub to it is probably a relatively small change. Whereas the sub enters a whole new world: a new domme, new fellow subs, possibly a new home... It's a lot, and there's probably more things to explore from his perspective than the domme's.
But it depends. If you have a bunch of ideas for how this will affect the domme more than the sub, then I'd say that's the way to go.