Actually, the dealer that I use recommends the Yamaha oil for the Honda's also. But to get either brand requires a long trip. Normally I will put 200 - 300 hours on my BF 225 each year, so that is three oil changes. Getting the Honda or Yamaha oil is a serious pain, so I go by what the owners manual says - any 10W-30 HD with API service category SG or higher.
Something to consider: There are probably a 100 or more brands out there in the US marketplace, but there are only about four significant manufacturers. So all those brands are often the same oil branded for a specific retailer.
I'm not sure whether Honda or Yamaha have any additional specifications on their branded oil - I suspect not - but the Owner's Manual simply states High detergent 10W-30 oil with an API certification of SG or higher.
The key is to change the oil at the recommended 100 hour interval, or every season, whichever comes first. If you think about it, if you average 30 MPH on your engine, then 100 hours is equivalent to 3000 miles. But that 3000 miles is under rather extreme conditions. It is somewhat equivalent to driving your car or truck, loaded to capacity, up hill, for 3000 miles in second gear.