Hi azhden.... I know a fair bit mate, particularly regarding COB and multichip LED's, I have 4 of the various kinds of VANQ chips, 2x 72w 7-band multichips(660,630,600,440,470,380,730) 1x 100w 7-band version and 1x 100w 380-840nm "full spectrum" phosphor technology. They do perform, believe me, very bright and excellent colour blending, single-point light source perfect for closet grows or small number of plants.. some of the chips are 32-35mil size red diodes which are apparently less efficient than single chips 1-3w chips, but it makes no difference as they are so tightly packed together as one diode they make up for it on overall intensity. heat is not an issue even though many people will tell you that COB's/multichips are a pain to keep cool with all the diodes so close together but that is bollocks azhden, I use stock CPU coolers found on ebay for under £5, they handle the 72w versions with ease and even the cheap ones can handle 65-85w of heat dissipation easily and are barely warm to the touch since LED's only emit a percentage of their wattage as heat itself.. as for the 100w versions I invested in some higher spec "arctic alpine" CPU coolers, the arctic alpine 11 plus is rated 100w TDP and 64 pro is 90-95w TDP and they handle the 100 watters nicely and are both under £10, although I'm told CPU coolers with many "thin fins" instead of thick fins are apparently better at dissipating heat away from the LED. I power them via 12v power supply and buck boost modules with constant current and voltage regulation, that means I can drive them at 30% 50% or up to 100% power!, and as you may know power supply and buck modules are peanuts on eBay, cost me maybe £20 for a 360w 12v regulated switching power supply and 2x 150w buck's, just try and find LED drivers at that wattage for that price.. Most of all azhden he price sells itself as all four cost me just over £100, and that's for over 300 actual watts, with heatsinks and power supply's I'm touching maybe £120, but I'm growing only 2 plants so maybe it's overkill, anyway they do perform well, viewing angle of chips are wide at 120 degrees without optics but I don't use optic as some light is lost through glass lens, to compensate I keep the plastic collimator on the chip to direct the light more which works better than without. For my 1-2 plant grow they are very effective and even better when paired with 30-50w cree xpg-2 modules or a couple of 2700k CFL's, distance from plants is 12 inches, and female WWxBB love them, best out of the bunch is the vanq 380-840nm phosphor LED, basically 45mil bridgelux chips covered with patent phosphor that imitates full broad range of wavelengths including UV+IR. My advice is to try CoB and multichips yourself, it will cost much less that some big-arse panel at similar power draw, "PICOGRAV" done a grow with VERO COB's, "bbspills" also with cree cxa3050, both of which proved very successful, I've even grew from start to finish with cheapo 50w eBay warm whites that even with lots of green still flower as good as any 200w CFL could, you'd be surprised what LED lighting can do to our beloved plants.. One last thing to epitomise where I'm coming from, I have just paid £39 for a 200w version of the 380-840nm phosphor on VANQ eBay, paired with a cree COB it is more than enough and the price itself should encourage more folks to try..
hope this helps you out a bit, like I say DIY is much cheaper than fully assembled panels, but if you do want to spend your money on a panel then Mars2, solar storm, or vipar are good brands wiournals behind them..
Best luck and regards Lewis..
