Thanks for your question.
My answer to whether this living arrangement would be a good idea depends in part on the relationship you have with your husband. If the two of you can agree to work together to ensure that the children have an environment that is as stable as possible despite the fact that all of you will not be living together as a family, it might be a do-able situation. But, if you and your husband are constantly bickering, especially about the kids (e.g., who will live where, how much time they will spend with each of you, etc., etc.), then I don't think an arrangement like this, where the kids are living in different places and going back and forth, would be a good idea.
Another concern is how the kids feel about this type of living arrangement. The separation or divorce of their parents is always an adjustment for kids, particularly if, as I mentioned earlier, they are moved around from one parent's residence to the other. If there is a short distance between your home and your husband's home, it might not be so disruptive as if you were to live in different towns or states.
Keep in mind that if either you or your husband later decides to file for divorce, the judge will consider the children's living arrangements since the time that you and he separated. If two kids continually live with him, and the other two continually live with you, the judge could end up making that a permanent arrangement (subject to modification at a later date, of course, but a custody modification is not without its own set of hassles).
Again, if everyone -- including the kids, if they are old enough to voice their preferences to the judge at a later date, if necessary in a divorce proceeding-- is agreeable to this type of arrangement, things will probably work out okay in the long run. The best indicator is how well you and your husband get along, and how capable you both are of making this work.
Hope this provides you with some insight. Good luck.