Honestly there are some things I like about them, some I don't. When I'm using the trailer for hauling building materials, hay, and other misc. stuff they are great. It is nice not having the ramps in the way all the time and I imagine with less wind resistance it makes for slightly better fuel economy.
However, for loading and unload equipment a lot they can get tiresome. They are fairly low to the ground so you really have to bend over to slide them in and out. Also once out you must then close the little doors again to keep them from interfering with the ramps during loading. If you were only hauling a piece of equipment a few times a month it wouldn't be an issue. Sometimes I load and unload equipment several times a day though.
As for the weight rating, they should be able to handle a ~6000lb piece of equipment, since that is about the cargo capacity of the trailer. The heaviest thing I've had on it was my F-150 trail rig which weighs about 5000lbs and the ramps are still good and straight.