Changing from 8-ways to 4-ways, should give you about 4-5 dB more signal [by having less loss].
Ok, just peeked into the attic.
I have two 8 way splitters connected to the SWM16.
4 lines feeding 2 HR24's, 1 HR20 and 1 H25 on one splitter, unused ports are terminated.
4 lines feeding 3 HR24's and Deca on the other splitter with all unused ports terminated on that splitter as well.
Would I be better served with two 4 way splitters, or am I splitting hairs?
Since half of your outputs [power] are being wasted into the terminations, this would "simply" mean a more efficient setup.