Having owned triple axle trailers, but not RVs, in those weight ranges I'd take the triple axle unit every time. Yes, a little more tire scrubbing on tight turns, but how many of those will you really make. As with most RVs the tires will age out long before they wear out.
When they do age out, yes it's two more tires to buy, but those are cheap compared to six DP tires and in my opinion are a cheap safety device. We've been traveling for six months out of the year all over the States for five years. Have seen a lot of trailers of all types (especially in hot weather) with a ruined tire on the side of the road. You could limp a heavy three axle trailer a ways down the road with a flat if you had to, but I wouldn't go anywhere with a heavy two axle trailer and one bad tire.
Was at a RV show in Phoenix three months ago and was impressed that some of the mfgs were putting Sailun tires on their 5th whl trailers.
Bill