The tone of the V.12 is generally bigger and more consistent than that of the Traditional reed. To evaluate the acoustic qualities of each type of reed, it is an interesting experiment to play them in various acoustic settings. Indeed, many professional clarinetists advise their pupils to keep both V.12 and Traditional reeds in their cases for the following reasons.
When playing in acoustics where the musician feels that his reed sounds too 'muted,' he may choose a traditional reed to give him a better response and increased flexibility. Conversely, a musician finding his tone a little too bright (the so-called clear tone), might change to a V.12 to achieve a darker, warmer sound without an aggressive edge.
In addition to the acoustic considerations there is also the matter of the precise tonal requirements of a particular piece to be taken into account. Indeed many professionals agree that one would not play the Brahms sonatas with the same tone as that used to perform the Rossini Variations.
These comments are relatively subjective, but if taken into account by the musician who is looking for a specific tone, his choice between V.l2 and Traditional reeds can be made more easily.