I always say let people grow with whatever on their first grow, I grew some great suff with cheap LED's back in the day, just not very much of it. They're a good way to get started but leave you wanting more pretty quick. Some of my best plants were grown under a burple LED/HPS hybrid light. As far as the spectrum, the listed wavelengths kind of reminds me of a viparspectra light but those only draw 276w, so your 340w should be better than that.
Just so you know the 1800w claim comes from the number of diodes multiplied by their wattage rating, the 340w is actually how much power the light uses.
Best Case i could see, you could reasonably veg and flower a 3x3, you'd be pushing it to fill a 4x4. Worst case, you forget to water for a week and kill everything. Or you have your light too close to the seedlings and that 410nm band might burn them, probably not though.