I have the 600 watt version and for me with the valve drive on full you get some nice warmth and extra harmonics but no real overdrive as such, just a small amount of breakup. It is however insanely powerful so the fact that I can’t push it fully may be a factor there, and being lower powered the 300 may achieve exactly what you’re after - or indeed the breakup that I get may be the crunch you want.
But that aside, they are a quality amp, I’d fully recommend the ABM EVO IV amps all day long, incredibly versatile and a real depth/weight to the sound.