I have used over a dozen of their different flavors over the last few years. They do lots of different lines suitable for brewing (compounds, swirls, artisan, and the purees that you mentioned. You have to account for the sugar content if added at bottling time, or just add it after primary fermentation and allow it enough time to fully ferment out. I happen to have a pineapple kolsch on tap right now, and just packaged a hazelnut brown as well. Both turned out great, and each used an Amoretti product in the recipe.
Raspberry is one flavour I think I would opt to use the real fruit. I feel it comes through fairly intense, even at 1/2# per gallon. I have had good luck cold crashing to drop the fruit to the bottom. Some of the flavors from Amoretti can come through as fake, or can linger on the palate for an unrealistically long time. I tend to use Amoretti as a boost to flavor from a subtle fruit addition, or in the case of unattainable fruits, or certain fruits and nuts which require too much processing that I'd rather not do.
Passionfruit and hazelnut were both intense and recognizable immediately. Both linger on the palette though which you may or may not enjoy. The pineapple and strawberry I found to be quite subtle, but worked excellent alongside the real fruit. This was my favourite use of amoretti. The fruit I used in each case did not come through to the level I wanted, but after the amoretti, it seemed to compliment the real fruit addition just perfectly. Mango was great, blueberry I personally found to be a little fake tasting, and the blood orange just did not really pair with the beer I used it in. Overall I have been very happy with them, just add to taste. The times I haven't enjoyed the beer was due to adding too much. The flavor did not seem to diminish over time either. Again, add to taste!... and I'm sure you will end up with a great beer no matter which route you take. Good luck.
