That's a step down from the A51. Diamond's are better regarded and the DS-100 would fit that space better for $300. I'd do the A51 and supplement.apollo horticulture 300w?????
I wouldn't do the cheap Chinese import unless money was tight. In that case I probably wouldn't do Apollo but TopLED instead because they have an online support forum which might reduce the possibility of being ignored if you have a problem.
What is your vertical space? Different lights need different distances to the canopy.