The sink rate of T-8, T-11 and T-14 are fairly close.
The main reason for using T-14 over lighter heads is the size and weight of the fly you will be lifting out of the water and casting.
You should also try just 5ft of T-14 and compare it with the MOW tip combination. In the lighter line weights the MOW tips seem to bog down the casting distances and loops.
This past weekend we experimented with a TFO
DC 12'6" 5/6 rod with a Rio
Skagit Flight 350gr and 8ft of T-8,,,,, it easily cast 120ft with very tight loops.