"The size of gig dictates the rig" used to be a standard rule for bassists. Appreciably, nowadays the bassist can use the same rig almost all of the time thats he`s comfortable with in a mix of the band, by the band right onstage. Or at least the folks I play live with do it that way. We play to each other in our own mix onstage and leave it to the reinforcement folks to take care of the outfield. I have been the, 6x15 Kustoms, Ryders,
dual cab 371 series Acoustics, SVT`s, Traynor monoblocks, and others, and dont miss them. Thankfully the newer reinforcement systems are more efficient and affordable enough to allow the band smaller, more efficient tools to work onstage, and play together like a band instead of trying to be a giant speaker system to cover the different venues. Smaller amps with decreased volumes onstage also allow the band to work more dynamically together and leave plenty of headroom for reinforcement, when it is needed, by an efficient FOH system. I used a small GK bass amp with 2 10's for several years doing a wide variety of venues. It was fine onstage.. and easy to control the tones in the prime mix perimeter. And the drummmer dosen't need to pound 2B marching sticks with the butt end to be heard either.
Also when the fundamentals are as loud as you`d think you'd like to hear them onstage, the mids and high end will be dropping off at a faster rate than the low end when the tones leave the stage, and quickly turn into muddy soup as they cover more distance..., in many arenas.