The Sekonic 308 is a great little meter. It is every bit as accurate as the more expensive Sekonic meters and will serve you just fine for most anything you want to do. It is more than "good enough". The more expensive Sekonic meters provide capabilities such as: tuning, wireless triggering, spot metering, strobe/ambient ratio analysis, multiple profiles, multiple ISO settings, and the like. These features can be very useful and convenient but aren't critical to determining proper exposure, which is ultimately what you want a meter to do. I'd stick with what you've got until you decide that you want or need the features of a more expensive meter.
People who do stupid things with dangerous substances often die! -me