"He who marches out of step hears another drum." ~ Ken Kesey
If you don't achieve the one hit you want will you pfp that 110 or will you then burn another screen with a 160 and PFP? We haven't printed these yet with white ink so I don' t know their ability to hold a good ink deposit but if you're confident then do the 110. The 160 PFP will put down about 25% more ink than the 110 with one stroke and the typical 110/81 PFP is bordering on too thick of an ink deposit, ESPECIALLY with the amount of puff in the rutland super poly.
The Gildan 100% Poly shirts fuzz up through the print like crazy, choose an ink with good fibre matt-down. Gloss likely won't be too much of a problem unless you put on a supper thick coat of ink or post-press/roller them.