I'd just suggest trying a beer where you make a healthy starter, say 2-3L. Compare to beer direct pitch. Then you'll have your own evidence. I've done this a couple of times and come back to the starter.
Primary #1: Border Crossing Vienna #2: Empty
Secondary #1: Berry Rhubarb Wine #2: Black Currant Wine #3:Empty
Kegged: Orange Pale Ale IV, Hidden Lake Nut Brown
Bottles: 2H IPA III, Carmel Apple Cider, Spruced Winter Warmer, Surly Bender clone, Big 50 Barleywine, Framboise Lambic, Dark Belgian Strong, Kicked by a Moose Scotch Ale, Russian Imperial Stout, Sparkling Elderflower Wine, Barolo Wine, On Deck: Ice Shanty Bock