We did a split stay last January. Some points to consider...
First, do the "lesser" resort first. It is more fun to upgrade during your vaction than to downgrade. We arrived on a Friday and did Fri-Sat night at Pop Century. Then we checked into a 1BR at OKW on Sunday.
Second, if you are not going to split the stay evenly, do the shorter of the two segments first. That way, you will have less to unpack, repack and re-unpack. For our next split stay (in 3 weeks) we are doing a studio for our arrival night and then a 1BR for the next 4 nights. We aren't switching resorts though so the move should be easy.
Third, if you have a car (which was our experience), pack it up in the morning and head over to your new resort to check in right away. I think you can check in as early as 7am. This way, if you have a
DDP, it is activated. You will also get your room assignment. It might not be ready, but you will know where to head when you return from the day's activities.
I think a split stay is probably easier with a car, but I do not think it would be much more of a hassle without one. I have become a "point miser" and it saves us quite a few points to do split stays between studios and 1BR's. We are planning on splitting our 5 night stays into 2 nights in a studio and 3 nights in a 1BR. We are usually so gung-ho the first two days that we don't spend much time in the room anyways. By day 3, we are ready to do some laundry, a little cooking and hang out more. Plus, it allows us to do a DDP for all or part of our stay.
I say go for it! You may see your vacation habits change!