I have had a very close look at both Ferretti and Azimut in my current search. I didn't have a chance to look at the 881 but I did in detail look at the 830 and 780.
First, if you are familiar with the smaller Azimut's, the 85 is a vastly different boat. It's finish level is much higher and the construction and specifications are "ship-like". The 85 and above are built at a different factory than the smaller boats.
While, size wise, the 85 is similar to the Ferretti 881, the 830 is closer in price to it. In looking at the 830, the quality of finish was inconsistent through the boat. Some items looked like tacked-on aftermarket products. Air intakes are on the outside of the hill, instead of being inboard of the bulwarks like the 85, thus being more exposed to salt water intake. Surprisingly, the Ferretti's lack lower rubrails. Engine room access on the 830 is quite poor, via ladders and the access to the crew quarters is very tight. Power, and water connections are underneath a step from the swimplatform, thus impeding access from those steps. Lastly, in the 830, the gyro stabilizers take away from space between the motors, resulting in an engine room that has about 5' of headroom. I think the only thing I liked about the 830 was the "teak beach", which offers great water sports storage. Unfortunately there is no access to the engine room, unlike on the 881.
On that note, the 881 is a much different boat but at a higher price point than the 830 and you may like the 881. When I compare the 830 to the Azimut 85, in terms of ship-like features, quality of finish, layout, thoughtfullness in design, I only come to the conclusion that Ferretti's are overpriced and living on past reputation.
I had a close look at the San Lorenzo 88 and I found that boat to be very well built and finished. If you were looking at the 881 RPH, I would suggest looking at the SL88. It surpassed Azimut and Ferretti and was even noticeably better than Ferretti's Custom Line, the more direct competition. That's another data point for me, questioning the current state of Ferretti's product.
My two cents!