Here’s the thing I get hung up on: the mfr says do X but a homebrewer says to do Y.
The mfr propagates the product, studies it, performs blind taste test/sensory analysis on it, stakes their business reputation on the outcomes which they have no control over when in the hands of the consumer.
…yet we’re supposed to disregard all the above, plus probably a whole lot more I omitted, because a homebrewer did some math and prefers the taste of his beers when underpitched (per the mfr recommendation).
I understand the mfr has profit to gain and is probably conservative because of the unknown variables, but I simply can’t get around the fact that they’ve studied this 10 ways from Sunday to develop their recommendation. We’re supposed to believe they are lying to us just to sell more yeast.
I don’t buy it. I’d go with the mfr. …but that’s just me. It’s your beer. Do what you want and let us know how it turned out.
Manufacturers test in a lab. Homebrewers test in real life situations. I will always trust my own experience.
And I'll add that the manufacturer doesn't disclose the goal of their recommended pitch rate. My money is that they're looking for a fast start to outcompete potential poor sanitization practices. Personally, that's not my primary concern, and I have great results with smaller pitches than the recommendations from the calculators I've used. YMMV of course.