I don't have any experience with Mars Hydro, but my HLG was about $2/watt purchased brand-new. Amortized over the anticipated 50-80,000 hour lifespan it makes sense for my setup.
Your lights are an excellent choice, and will grow nice bud for you. Had I not gone for the DIY, I most likely would have done something similar, maybe even identical. Although I really like the Mars Hydro SP3000 for my 2x4, I like the light distribution of the boards better, and I like the option of two separately adjustable heights in the 2x4, so I might have gone with a pair of HLG's.
However, I confess a bias to DIY, and to cheap if it works. I also like the independent bulbs, each with its own ballast, which eliminates the risk of general ballast failure which happens sometimes even with the nice Meanwell units. If one of my bulbs fails (no sign of that after two grows), I just pop down to the hardware store for a replacement. Actually, I have spares, so even a trip to the store would not be needed.
As to LED efficiency, quite aside from the length of time power savings would take to pay for the better LED, my growdrobe needs heat because I grow in the winter in my basement. If the light did not supply it, an electric heater would have to. In fact, I often have to supplement with a heater even with the screw in bulbs. Consequently, a more electrically efficient light would do little or nothing for the overall efficiency of my particular grow. Other grows, might benefit from better efficiency, but the arithmetic needs to be done on the entire grow setup, not just the led efficiency.
As to the 50,000 hour lifespan, let's see - at <2000 hrs/yr for my grow, that would be another 25 or so years. I'll sadly, for me at least, be long dead by then even if covid does not get me.
