I have the 500. It’s a huge sounding beast, really versatile EQ, and the compressor (sort-of-gain/fattener) is an absolute gem. Cuts though the mix like a knife through butter, and snarls without being fuzzy. If I was replacing it, I’d go for the 300 version as the 500 is silly loud - don’t think I’ve had it past the second notch on the dial!
Studio recording using a four stroke here (was mic-ed up with about 20% blend from the DI in the mix, and nothing else added).