I have a single axle EZ Loader which I believe came with the boat new. It is of very high quality almost all aluminum construction, and has adequate capacity for the boat, but I don't really know what the pros and cons are on singe vs double axle. Single axle, a tire blows and the rim is on the ground with half the weight of the boat on it. Likely to damage rim.
But, with double axle, if a tire goes flat, seems to me you might not know it until the newly overloaded tire on that side overheats and also blows. I had two blowouts in consecutive days before I learned about trailer tire quality, and maybe by luck did not damage the rims.
Based on my experience and recent discussion of trailer tires, it seems we should be replacing our tires at least every four years. Double axle double cost. Probably a bit of a Ford vs Chevy argument.
Larry