The frequency shift that you mention reduces the efficiency by a factor equal with the ratio of the frequencies.
When making green light out of blue light the efficiency cannot exceed about 83% and when making red light out of blue light the efficiency cannot exceed about 70%.
Real efficiencies of the fluorescent conversion are much less.
Moreover, there is no hard limit for improving the efficiency of an incandescent light emitter with better infrared filters and better thermal insulation.
Therefore, when the comparison is made for a great enough frequency bandwidth, the efficiency of an incandescent light emitter coupled with a lossless optical filter should be able to exceed even the efficiency of a LED without fluorescent phosphor.
The best colored LEDs can reach an efficiency of 70%, but only at very low output power densities. When the output power density is increased, to reduce the cost of a LED lamp by using a smaller LED, the efficiency drops a lot, to levels that should not be hard to exceed with a filtered incandescent lamp.
The LEDs and the laser diodes are unbeatable in efficiency when it is desired to produce light within a narrow frequency band, which is not the case for lighting applications.
When making green light out of blue light the efficiency cannot exceed about 83% and when making red light out of blue light the efficiency cannot exceed about 70%.
Real efficiencies of the fluorescent conversion are much less.
Moreover, there is no hard limit for improving the efficiency of an incandescent light emitter with better infrared filters and better thermal insulation.
Therefore, when the comparison is made for a great enough frequency bandwidth, the efficiency of an incandescent light emitter coupled with a lossless optical filter should be able to exceed even the efficiency of a LED without fluorescent phosphor.
The best colored LEDs can reach an efficiency of 70%, but only at very low output power densities. When the output power density is increased, to reduce the cost of a LED lamp by using a smaller LED, the efficiency drops a lot, to levels that should not be hard to exceed with a filtered incandescent lamp.
The LEDs and the laser diodes are unbeatable in efficiency when it is desired to produce light within a narrow frequency band, which is not the case for lighting applications.