I agree with questioning longevity. I am using a BML SPYDR 600 which is now 5 years old, but probably only has 5 full grows under it. I had to send one bar back for repair about a year ago, and was told parts were not going to be available any longer.
I also have several Amare Technology panels 230, 260 < these having the most on time, and a Pro 3 , which has 3 cobs surrounded by key spectrum monos (MSRP $695, but discounted 25% = $525 + shipping). now on its 3rd grow in a 2 x 4 tent, which seems perfect for it. True 300w
https://www.amaretechnology.com/product-page/solarpro-sp300-pro3
My preference is bars, like my SPYDR 600. A style that AT is currently embracing, but a Bar 8 MSRP is $1700 (~ $1300 with discount), no price available for the Bar 6, but likely ~ 3/4 of the Bar 8 or ~ $995 with discount.
With most 3+ yo lights, their leds are virtually obsolescent as diode advancement moves along at seemingly warp speed. Unlike other products, which by law have to keep parts inventory a minimum of X years, led mfgs are not held accountable
A SF 4000 MSRP is $529, dimensions provided state 25 x 21; seems like it would be much bigger. Anybody? not that the 2 are apples to apples in coverage or wattage, AND, although I much prefer bars, even if the SFs only last 3 years, the amount of finished meds you should get, IMHO, makes replacing them then a no brainer, and they are probably going to be considerably improved by then, not that I see anything wrong with them now.
Should I ramp up again to multiple tents I will likely get one
hth