u/Central_Incisor

This is more of a general instruction question.

Many of you have seen the pBugle and is advertised for beginning brass instruction. Another group Brass for Beginners have also gone the valveless route and make a plastic natural trumpet that has a longer air column and easier to  reach partials again for beginning brass instruction. Now Yamaha has a bugle-like instrument in Bb called the Trova to fill the same role. 

So I guess the question is there any evidence that these instraments fill any need?