Wallace TWC-511 Tenor Tromb Wah Mute

The Wallace TWC-511 Tenor Tromb Wah Mute is a big and heavy mute. It is well-made, with some clever ideas, but also some basic errors of design.
Plus points:
+ There is a wing that runs around the mute, which allows the player to hold it very comfortably with just one hand, to insert it into the bell of the instrument.
+ The large mute size provides a nice, round sound in all registers, including the bass notes.
+ The thick synthetic foam pad helps to avoid the common problem of wah-wah mutes: that they easily detach from the instrument and fall on the floor.
Now, the bad things:
-- Because of its size, the mute is really heavy, and the player feels that after a few minutes of playing.
-- The synthetic foam pad has also disadvantages, mainly because it is thicker and softer than the traditional cork pad. First, it deteriorates faster than the traditional cork pad. Second, the big and heavy mute becomes unstable, moving around from one side to the other, especially when operating it with the hand to produce the "wah-wah" effect.
-- Personally, I find the big size of the mute somewhat uncomfortable to operate with the hand to produce the "wah-wah" effect. Maybe somebody with bigger hands may find it better.
-- There are several serious acoustic flaws with the mute. The first is that the bell of its stem (the nice blue cup in the centre) is way too small. It is just a bit bigger than the bell of my trumpet wah-wah mute. As a result, in such a huge mute it is difficult to operate and produce a meagre "wah-wah" sound.
-- The second acoustic flaw is that the length of the stem is too short. To produce a good wah-wah effect, the stem must go deep inside the mute, approaching its rear end. However, in the TWC-511 the stem ends inside the large resonating chamber of the mute. As a result, the wah-wah effect becomes even more poor, since there is no significant change in pressure/impedance when the hand closes the stem bell. In other words, the wah-wah does not work. It is a frustratingly muffled wah-wah.
-- When the mute is played without the stem, it sounds too quiet, even when blowing on full power. It sounds just a bit louder than a practice mute. It is impossible to play loud with it, especially on the high notes. I guess that it has something to do with the diameter of the stem hole, that may me disproportionately small for a mute as big as the TWC-511.

To sum up: it is heavy. It sounds nice without the stem, but it is too quiet, just a bit louder than a practice mute. With the stem, it sounds nice, but the wah-wah effect is VERY poor. Already in the middle range it is almost imperceptible and on high notes it is negligible. Finally, the thick foam pad allows it to fit all kinds of bells, but the mute becomes wobbly, especially when trying to operate the wah-wah effect.
All in all, it has potential, but its current design does not work well and needs lots of improvements in order to become a good wah-wah mute.