There has been a better led grow light every 6 months for years. You think they are done improving?
No, I don't think there done improving, certainly not, but it's getting dialed in very well, and the only things that are going to probably improve at this point are configurations. I haven't looked into the roadmaps for the diodes, but these new gens are pretty damn efficient, and it will probably be a bit until something surpasses their efficiency, I've been doing LED's for almost 10 years now.
TBH, I'm surprised that the 2w are so efficiect, but it's pretty simple when you think of it. It just boils down to spreading them out more. Maybe one day they'll come out with some 1.75's or 2.5's that are perhaps a little more so, but I think it's reaching it's optimum.
There's ton's of research and studies being done on multiple levels behind this crap for a good amount of time. You can only make a light "so efficient", it's not like there going to come out with ones that have much more efficiency, (it's very incremental) and their most certainly reaching a peak.
As for samsungs numbers, some of it's a bunch of rubbish, because this has been an industry that's overstated things from the beginning. There always "streching" the truth a bit.