How efficient are RGB LED strips?
Costs of COB, RGB and phosphor

Those particular LEDs are individually addressible, and that brings a host of efficiency problems along.  


The on-LED controller needs its own power.  
Supply power is not a voltage that is ideal for LEDs - the LEDs want ~3V but the supply is ~5V.  That's most likely a linear driver (I really doubt that chip includes the chokes for 3 buck converters), you are chopping 5V down to 3V linearly, discarding 40% of the energy before it even gets to the emitter proper. 
Power distribution is at only 5V, which is extremely vulnerable to transmission losses. I've seen designs that called for 350kcmil + and - buses. You gotta be kidding.


The upshot is that individually addressable LEDs are optimized for building billboards and stadium TVs, not illumination.



Now if you want to go for the non-addressible RGB LED strips, they mostly cure these problems.  No controller to waste power.  Distribution is at 12V (somewhat better) or 24V (much better). 12V is better for powering a stack of 3 LEDs, you maybe lose 20% to the limiting resistor.

That said, the notchy R/G/B light is not going to look quite right to everyone, and won't have an excellent CRI.  It's not white light, it's just designed to trick the eye into looking white. I would expect it to give the same kind of eye fatigue you get from looking at a screen for a long time.  

On the upside, since the LED is internally doped to make that specific color, it's not using a phosphor to make the color, so it's not paying phosphor losses. 



Now if you go with single-color white LEDs, those actually make blue internally and use phosphors to convert the blue into a full spectrum.  Phosphors have an efficiency loss (and they cost money). That's why bluer light LEDs (6000k) are cheaper and more efficient than less blue LEDs (2700k). 

Don't forget aiming

There's one more angle (heh) to efficiency.  An old bulb emits spherical light.  It even illuminates the bottom of its own socket. But nobody wants to light a sphere.  They typically want a cone or wedge ranging from 8-120 degrees.  Historically you solved that with inefficient reflectors.  

LEDs are the first to give a cone of light, of roughly 140-160 degrees. And that lends itself to optical (lens) aiming, which is near 100% efficient. Now you don't have to light up the wall, the sky, the neighbor's bedroom window - you can just light the subject.  That is a gigantic efficiency advantage that you should make full use of.