While
I'm still not even sure if I'll keep the D-Tuner ultimately, I do have to take exception to the highlighted 1/2 of your argument. I
do applaud your willingness to try the product, though!
Assuming that an electric bass guitar isn't being used in a symphonic or chamber music performance, and that the nature and flow of a typical pop/rock/etc... ("popular" music genre) concert is
very different than the environment you reference- I think that your point "a)" is a stretch. Plus, given this differentiation, point "b)" may be negated as well. I agree that audible tuning doesn't
necessarily make one "unprofessional", however in the performance styles that bass guitar is a staple- it
does show a lack of preparation and care.
It's rare that I've been to a top-tier "popular-genre" concert where a musician
planned on audibly tuning on-stage in the middle of a performance. Furthermore, the fact that a musician opts to use silent electronic tuning, or some other method of discreet tuning, should not bring one to the conclusion that said instrumentalist is incapable of tuning otherwise. Silent tuning is more of a courtesy to the other performers and the audience! In a symphonic ensemble, or other "traditional" ensemble (chamber orchestra, string quartet, etc...), the collective pre-performance tuning has become, in fact, a part of the performance! It is not only for the utility of the performers, but an expected element of the concert experience. Not so with the vast majority of genres featuring electric bass!