Dave said it pretty well...."cheaper"... not better.
I have to agree with Dave on something else too... I think the twin 150s on my Rosborough, are over powering the boat. Some like it, but, I actually liked the 230 hp range, and, at the same time, think 180 would also be a nice hp range for the heavier, better built RF-246, but, no one was building a 4 stoke motor with counter rotating props on the 25" shafts in the 90 hp range. When boating in all water conditions, those heavier built boats have a much more pleasant ride too...sort of like separation of a Nova and a Cadillac if you will...for you GM folks.
I actually picked the twin 115s rather than twin 90s, as to get the counter rotating props... which with twin motors is nice...if you have owned and worked them, you understand this. So, it was not the horsepower, but rather the balance, the counter rotation, and the I like twin motors factor...
As for the trailers... yes, many tow the RF-246 with twin axles...and, with only surge breaks. Again, I have had the opportunity to own both, under the RF-246...and, again, I like being able to have brakes towing down hill over the mountains...and, when backing down the ramps, and, the ability to "adjust" the amount of breaking in wet, or heavy traffic slower conditions... Again, not cheaper, but, better for the way I enjoy "using" my boat, and, I exchanged my twin axle for again, the triple axle with electric over hydraulic brakes... and again, a good quality, safety, and control issue, not cheaper.
So, just so many boats... so many options...and again...that is why I have and generally do own....more than one boat. I recommend that to others too.
Good Day.