Guess they have good reason.

Guessing Mecury's 200 Fourstrokes not the Pro XS's since the 200 Pro XS is a V8.
They are 475# *(lightest model they claim) according to the PDF spec sheet.
SeaPros are heavier, they have a bigger gearcase in the 200HP VS the regular 200HP Fourstroke version if you aren't aware.

So 2 of those = 950#.
Whereas a 400HP V10 Verado is 695#.

So seems a shame though to not be able to power it with the V10.
Other than the advantage of twins in a offshore situation.

The 28 was originally designed for a single, but demand for twins made them re-engineer the transom and systems to support it. The V10 will be available sometime in 2024 I am told.

The twins on the 28's are the standard 200 four strokes. The Brabus boats get the XS Pro's at a huge premium.

Imo
anything 29 and over besides very few exceptions i would only go twin !

There is an Axopar dealer in San Diego (America's Cup Harbor) where I keep my Formula 280SS - they're beautiful boats. Since you are already spending big money on a new high-end boat, I highly recommend you go with twins not only for the safety factor, but also the performance gains and better/easier control/maneuverability around the docks. A single engine on the back of a 28' boat around the docks can get very tricky if the wind and current conditions are unfavorable. When I was looking for a boat to keep down in San Diego, I wanted to keep it under 30' to fit in dry stack and I wouldn't have even considered a single engine rig, even though there are several single engine models to choose from under 30'. Twins are the only way to go once you get over about 25' imo.

Congrats on the Axopar! I love their boats.
I agree with getting twins due to handling at the docks and not being stranded if you lose an engine. I'm sure it'll help resale value in the future also.

Thanks for everyone's feedback! I am certainly leaning towards the twins, especially since I have already sea trialed a 28 with twins. Just for comparisons sake I am having the broker see if I can get some stick time in a single.

But, all of your arguments about redundancy, performance, maneuvering are in the right direction of my thinking too.

I boat on the Great Lakes and have lost a drive twice. The first time, I had to wait 4 hours for Sea Tow. The second time I was fortunate enough to flag another boater and they towed me 15 miles to the nearest harbor. Next boat will have twins.