Fyrman is right with the torflex being a little more forgiving with a lighter load. The biggest problem with Torflex axles are that on a tandem or triple, they have no way of equalizing the load between the axles like leaf springs with boomerang shackles do.
The suspension action is independant for each torflex axle on a tandem set up. If you tow the a torflex trailer with the tongue down, you may be overloading the front axle and if you tow with the tongue high you may overload the rear axle. So with Torflex axles, it is imparative that you have the trailer towing flat as to equalize the load between the axles. So hitch height becomes very important with a torflex trailer. With a leaf spring tandem trailer the center shackle equalizes the load on the axles regardless of tongue height. This is kind of nice when you are towing with a 4x4 and don't want to use those huge drop hitches. If you are looking at a single set up then go Torflex all the way as they require less maintance and will probably last as long as your trailer. On a tandem, it really depends on your circumstance. One last thing torflex axles also give you better clearance.