the previous 4 times I've started up with a 1st gen, I have had attenuation issues, however, in my recent Centennial IPA - I got 79.7% AA with 1st gen.
I was lazy this time - 12gal batch, 2L on stir plate with 1 pack, then decant and split the cake into 2 - 2L flasks added 2L of fresh wort and let er rip for 2 days.
One thing I did differently this time was to pitch about 63-64 and ferment ~65df instead of pitching colder and keeping it around 62.