The bassist I replaced was a 51-year old guy with an attitude problem that played, well, like an older guy. He obviously was influenced by 50's and 60's rock, which is okay, but in a modern alternative band, he just didn't fit. Also, seeing as the average age for the band at the time was 22, he was out of place.
I've been told my lines compliment the music a lot more, my vocal abilities are valuable, and that I am a very entertaining person to watch. I've also been told that I am very confident with chops to back it, but that I don't solo enough.
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I have temp'd for another local band that is very Tool-influenced. Their bassist doesn't move much and plays rather simple lines with a mellow tone on an Ibanez through a Hartke half stack (1x15). I played a lot of complicated lines (tastefully, of course) on a stingray with a lot of upper mid and treble bite to it to make it sound more aggressive (almost Justin Chancellor-ish). Although I didn't replace him, I get the feeling they prefer me and my stage presence to his.