First, thank you for serving our country.
Donzi vs. U-XX. Both are good boats. My experience with Volvo I/Os has been great and I wouldn't make a decision NOT to buy a boat because it has a Volvo. As mentioned, they are a STRONG drive. What have you been "lusting" after (boat wise
)? Would you feel like you "settled" if you bought a Four Winns?
Trim tabs are great, and there is no real down side. Many have done fine without them. I have had them on both my 18s, and I added them to my 16.
How are you going to boat? Alone? With 3 or 4 friends? A 16 is a fun boat for the driver. It is OK with 1 other person, but the cockpit is shallow, so the L-Lounge doesn't really make a very comfortable seat. The 18 is somewhat more comfortable for back seat passengers, and rides like a bigger boat. It has been said that you ride "on" a 16, and "in" a 22, with the 18 in between. A Minx (20') would be something to consider. They are a great boat.
If a 16 would do, I would find a way to get another $1,500 and buy Ralph's 16. V8, Mercruiser, and just about perfect. And it is a 1995. I will have over $20K in my 1967 rebuild before it is as nice as that one.
Ralph's ad:
http://www.donzi.net/forums/showthread.php?t=64277