My thoughts for what it's worth.
Poly 52/SynGut 56 will play tighter than all SynGut 56. Drop another 2-4 lbs off the Poly/SynGut to make it play similar. For example Poly50/SynGut54 or Poly48/SynGut52 will play like all SynGut56.
I also never string poly above 52 lbs - my max is poly52/SynGut57 (5 lb differential between M and X). This feels very tight/stiff in my mid+