It's a bit low and the size of the light isn't the best because leds tend to go straight down instead of a lot of diffusion. Lately, i've set all my planted systems up with a finnex fuge ray. this is a very good bright light and one of the top recomended for planted aquariums. It's also close to your price, only about $15 more.
Oh, woops, that was a mistake on my part. I would go the full 20 inch length if I were you. And yes it is more expensive, but i've wasted more money in past buying lights that might be okay when I would've been better buying the one I need.