What exactly is the difference between Domestic Chores and Lifehacks? It seems to me there should be a lot of overlap between the two.
The comparison did cross my mind when making the proposal, however, although there is a crossover in the questions that are on-topic there is a significant difference in the answers you might expect to receive.
On Lifehacks, answers are specifically supposed to avoid 'proper' solutions, and try and find interesting ways to deal with common problems without using the proper tools.
On this proposal, the type of answers that we're looking for are the correct solutions, using the best tools and practices.
The difference is that it will attract a different crowd. And that's the best reason to have two separate sites. I don't really care for Lifehacks, but I think I would ask on Domestic now and then if the advice there is better than a uniform "scrub it with baking soda". And I suspect the Lifehacks people would have a similar feeling for a "boring" domestic site.
Note that many sites on the network have an overlap in scope, and still function well. Especially pertinent for this case, many questions from Lifehacks would be on topic for cooking, and some have been asked on both, and I think even gotten similar answers. This has never been a problem for us on Cooking, and as far as I can tell, Lifehacks is OK with it too.