I owned an Andreja Premium for many wonderful years, but decided to take the plunge to a double boiler, and am so glad I did. Visually, this is s slightly larger and more refined version of the Andreja Premium, which I liked vey much, so I am very happy with that aspect of the machine. Popping the hood, the insides are awesome--great construction, well spaced, industrial strength. What I didn't expect, and am very happy about, is the value of the commercial pump, it is a nice upgrade from the Premium.
I bought the Duetto to get more consistent pulls, and that is exactly what I got. The Duetto really delivers. I definitely got great shots out of the Premium, and would, and do, recommend it highly. But the Duetto, at least for me, takes it to a new level. By being so consistent, the Duetto has helped me get my tamp wired, and encouraged me to micro adjust the grind. Can't say I get a 'god shot' every time (I'm just a part-timer), but I never get less than a very good shot, and when when it isn't the best I can pretty accurately predict why and adjust. It has also encouraged me to adjust my roasting, and small modifications of my bean mix are now quite easy to taste.
It has taken me 15+ years and 6 espresso machines to get where I am (okay, I'm a slow learner). The Duetto is probably not the machine I would recommend for a 'first timer,' that is sort of like buying a Lotus to drive to the supermarket for groceries. But if you a serious about your espresso, and have the cash, this is truly a wonderful machine. I recommend it highly.