I made a triple berry DB last year from Costco's Kirkland triple berry fruit. I bottled it in March of 2021. We opened a bottle yesterday at Thanksgiving dinner and it was delicious! The aging definitely smoothed it out.
I used 12 lbs of fruit for 6 gallons, which is about 1.5 times the amount of fruit in the original recipe, if I recall correctly. I made my first batch according to the recipe (tweaked to make 3 gallons instead of 5) and it was a bit light on fruit for my taste.