Our trips are USUALLY only 5-6 nights, so normally we wouldn't do a split stay. Although DH and I did do a 3-night split stay in July (without kids). But that was because it was a last-minute trip, we wanted BWV (we're DVC members) but it was only available 2 nights, so we did 1 night at SSR and 2 nights at BWV. This upcoming trip next month, we're staying 9 nights. First staying 5 nights at BWV (original trip plan). Then we added on 4 more nights but (1) didn't have enough points for BWV and (2) Two people are only staying the first 5 nights, which means we will move from a 2-bedroom (with 7 people) to a 1-bedroom (5 people). We are currently booked at OKW with a wait-list for Kidani. (Kidani, BLT and OKW are the only DVC with 1-bedrooms that accommodate 5 people.)
But it's really easy because Disney will transfer your luggage for you! Just have to keep in mind that (1) You may have up to 5 hours without a room on the day of your switch between check-out and check-in and (2) It could be even later for your luggage to arrive at the new resort. Just plan accordingly, and it's not a big deal.