I would have to disagree, you can master a bass, everything from levels to strings, to the attack you use can be considered mastering the instrument, also the feel of neck, the weight of the body, everything about it, its like a flat head screw driver and a phillips head screw driver, sure they do similar jobs, but you can't stick the phillips head into a flat head screw. Its the same thing with basses, if you can find that "swiss army knife"(something that can do anyjob) you won't need anything else (a one trick pony isn't worth the money). If you get hung up on having more and you're ready to purchase something, always be on the look out for you're swiss army knife, you never know.