There is a lot that goes into it. First is the weight. Some double axle trailers might be maxed out. Where a triple will have room for more weight. For me, the 300DA with trailer comes in at 12k lbs. The trailer is rated at 15k. So that leaves me with some wiggle room when loading all the stuff that everybody else "needs" to have.
My triple axle runs down the road great. As long as I'm not trying to take a corner fast. A hair pin type corner and she is scrubbing a little more than I like. And a street corner or pulling into a driveway and it's scrubbing the rear two axles the whole way. So tires will be heavily worn and need replaced more often.
Another thing, I have surge brakes. If you do go with a triple, get the electric over hydraulic. It's on the list of need to do but due to the cost to retrofit, it's low on the list.
And make sure you have the rig to tow it. Don't always rely on the info from the dealer. I seen an ad the other day that the new F150 can tow 10k with the new electric motor. I wouldn't tow that weight with a half ton. Just not that safe in the real world where traffic can get crazy. If in doubt, ask on a forums about real world experiences or friends and family.