Considerable improvement over the old days. How much of that would you attribute to experience?
This grow seems to be going better than my first LED attempt, but I'm not sure about the improvement over my old vertical HPS set-up. I grew vertical for over a decade, but I've been growing indoors and out, on and off for the past 30 years.
However, until I started my first LED grow, I hadn't grown anything for about three years, so there was a bit of a learning curve with the LEDs, as well as having to "clear out the cobwebs" in terms of growing again. I've never grown anything but pot, so I'm not exactly a keen gardener!
I think what you're really asking, though, is what do I think of LED vs HID. Well, I got close to a pound on my first LED grow under 400w (though I started off driving them a bit higher, gradually reducing power until I found the sweet spot), so on numbers alone that's just over 1gpw compared to my average 1.3-1.4gpw in my vertical HPS set-up. I grow in a hot climate without aircon or CO2, in coco run-to-waste, and always multi-cropping (usually three or four different strains), so my old HPS numbers weren't too shabby.
I think this grow may rival that, but there are always other factors to consider like strains, time of year (temperature/humidity in a non-controlled room), flowering time etc. So on face value, yes, I now believe LEDs are more efficient and will only get better.
But . . . while the plants and buds look good, and the smoke is up there, I have noticed the plants I've been growing under LED just don't seem to have the same oil production or aroma I'm familiar with. It just doesn't seem to be quite "there". I can't quite put my finger on it, so I've given a couple of clones to a friend of mine who grows commercially under HIDs to compare the final product.
One theory is the lack of UVA/B produced by LED compared to HID. Contrary to popular belief, HPS elements
do produce UV light and that's the reason the bulbs have a bit of iron in the glass (giving it that green tinge) to filter out. But some escapes and is measurable. Not as much as MH and nowhere near the same as Mercury Vapour, but more than LED.
I've been tempted to throw a couple of UV reptile bulbs in my current grow to see if they make any difference, but I'm going to wait until I see the results of the same clones grown under HPS first.