This lens is incredibly sharp and produces nearly no coma. Also the image is super flat and the lens also works for full frame cameras. For its high image quality it‘s also used by some more advanced astrophotographers.
As I bought it new for 400€ this was a no brainer because we can also use it for ‘normal’ photography.
I‘m sure your lens works well for many nebulae!
I can recommend this online telescope simulator where you can simulate the field of view with your equipment. Your 300mm lens should be absolutely perfect