It is like having one litre water bottle hanging from your hands on front of you. Even the trumpet do not weigh as much as many other brass instruments it is held further from the body and the torque makes the weight feel a lot more heavy… All the time when you play you do have the tension in your arms, shoulder, neck and back. It is there even if you do not feel it or think about it.
Of course, you can hold the trumpet and your arms in playing position that way. However, if you can avoid this, the important question is, is there really any sense keep on doing that? Would the playing be better in the long run if your arms, shoulders, neck and back could be more relaxed?
ERGObrass works with both piston and rotary valved trumpets and also with the cornet and even most flugel horns. However, the normal trumpet plate is designed for the piston trumpet, for the other types you need a special plate for each type. You can get them separately when ordering the trumpet set.