As far as the discussion was going with respect to "enhancement" effects or phytochrome manipulation i was considering them pointless. But then just for supplimentation lighting i would place them under the same classification. You are talking about adding an additional energy which because of the stoke shift loss, places red flurescents well under the traditional level of efficiency for fluros. You are talking about single digit percentage increases in total flux. There are better ways to compliment main lighting. For example using standard fluros (neutral) is more effective than red, because they do not have to loose energy through wavelength mismatch conversion. But its of course more benefical to just use the same light technology as the main source to increase the total flux. Whether thats from additional sources or increasing the original source size. With that said i mean no disrespect.
The absorbance of blue by light harvesting pigments is actually higher than red. But the quantum efficiency is naturally sloping due to the wavelength mismatch (planks equation). Many people take too literally the quantum response of light on single leave measurements. But forget the variables which occur with whole plant photosynthesis. As far as current research has strongly shown, light quantity is more important than light quality (with broadband sources). This has to do with factors such as the seive and scattering effect. Where under whole plant irradiance, the determing factor for leaf anatomy and growth is the total flux rather than spectral characteristics (bruce bugbee).
During flowering, plants do not exhibit photomorphological characteristics (except for UV manipulation with trichomes), which is why monochromatic light sources can be used with no negative effects during florescence.
I dont know any mainstream far red light products unfortunately, it does seem to be a "do it yourself" solution, as the method is so specific to how its applied.