I had a 23 Baja with a 454. Nice boat, just wanted to go bigger and faster. I moved up to a 27 Fountain with a single 502. Better boat, better ride and faster. I came across a deal and moved up to a 29 Fountain with a single 500hp. Better ride, faster, and more room in the cockpit. I got the "bigger and better" bug again and decided to go 32' to 35' with twins. I am now in a 35 Fountain Lightning with 500hp's. The gas is not that much more than the 29' with the single. I LOVE THE TWINS AND WILL NEVER GO BACK TO A SINGLE. Docking is a breeze and the sound of the twins turns heads. The engine compartment has plenty of room to work on the engines. I do all of my maintenance, oil, filters, plugs, etc, and I can get into the engine compartment with ease and do not have to stand on my head to get to things. I boat on Smith Mountain Lake in Virginia so the water does'nt get that rough except on holiday weekends and the ride is great.
Just my .02

In most cases, I would think the biggest advantage would be having your power running through 2 Bravo drives, rather than worrying about putting big HP through a single Bravo, or spending a bunch more on a beefier drive. Just about everyone on here with a larger single engine boat appears to run into drive issues at some point, a pair of 496's or 502's with Bravo 1's would be pretty much the same cost up front as a single blue motor and fancy drive, and easier/ more affordable to deal with given the same size/ weight boat.

If you run in big water, or true offshore, having the piece of mind of an extra engine and drive makes it a no-brainer if you can afford the fuel.

Also, If you tow, especially longer distances, don't forget about the bigger tow rig and fuel cost needed just to get to the water if you move up from a 25' to a 30'+ boat.

i dont get why everyone is scared of a cost in fuel in twins vs single... heres an example. 96 single 548ci 650 hp 28 pantera went 68mph and got 1.5 mpg. my 94 twin stock efi 502mag goes 77mph and gets 2.5mpg so where is this massive fuel consumption ????

Never understood it either.

For me it was a big difference but I went from 360 hp to 1000 hp on my old boat went to kelleys from my dock and back 4 times on $100. My new boat can make it only one time there and back.

Fuel consumption isn't complete witch craft, can't it be somewhat "calculated"? I believe 1 hp takes .008 gph to make as a general estimate. So at any given cruise speed whatever power it takes to move it is what it's burning. Twins add weight and additional drag through a second drive so it will take a little more fuel, but probably not too noticeably much.

However, this takes no consideration for efficiencies of the engine at different RPM's as well as carb vs efi etc which will alter this. So if you have twin EFI's at more efficient rpm's to make the total power than a carbed single I'm sure you can get better efficiency.

twins may add more weight but way less prop slip resulting in lower rpm higher cruising speeds