I'd focus on the room, rez, environment (de-hu, AC, Fans, genetics, timers, potts ect. Unless you have most of that already.
10x12 bedroom or high ceiling commercial space?
4500, can start up a 10x12 quite nicely.
Or if you have most of what you need then your led research is key now.
Electrical efficiency is not everything nor is spectrum. Its a nice split down the middle that has provided the results.
Minimum spectrum play I'd use would be 35k, 660, 740nm (need the blue & the n/ir or 740nm, 660+740=Emmerson Effect+). Simple, highly efficient & effective. Check heatsinks for proper cooling (no such thing as to much heat dissipation). If there's nothing to it, it probably won't last. You'll want covered diodes. Avoid Lights with Drivers mounted directly to the bar or board. If encased then its all in one & will have to go with reputation of build quality vs service + warranty. Reputation helps but isn't everything. There are plenty of good companies not getting the credit they deserve.
Efficacy #'s do not tell the whole story.
When judging solely off posted efficiency #'s, Spectrum is often overlooked. As well as fixture design which often effects canopy coverage. Though its good to have when it is true as a baseline. The point is to double your photons per watt consumed while increasing quality.
Some are finding CMH + LED to work well. Generally those using white or wh/r leds as the cmh fills the desired gaps, led provides efficiency, photons & often some red with a smoother curve, so they compliment each other.
Companies recently started making efficient leds that include the full spectrum or darn close. I have yet to meet a person using one. Mine is pre-paid & Ima waitin patiently.
Plenty of options for efficient leds nowadays. Only a few for full spectrum which maximizes the plants morphological abilities. Remember- efficiency vs spectrum to get the best of both.
Warrenty & reputation. Lack of reputation isn't so bad as the innovators or often ignored by the majorities who are used to & happy with what they have. Then copied by the more popular companies later.
Bad reps & multiple complaints should be avoided no matter what. Cheap Burples or 200w/1200w equivalents should be burned.
Goodluck!
1800w of properly enhanced spectrum bar lights (16 bars) just gave me 7.3#'s. X2 lights, 12x4 of mostly canopy. X4 plants. Bag appeal & density through the roof.
Just don't see myself doing that with Any HPS.
