No I have not and not likely will in the near future. I slowed down led testing a lot since last year, I have grown a lot less motivated to do loads of them. Still have a few leds in the pipeline and this is not one of them.
But I do have an educated guess for this led. The comparison is not fair with the 660nm XP-E2 but because its larger die size it must be compared to the 660nm XP-G3. I tested that one a year ago but did not do a proper BLF-post of that test. But here are the numbers for reference:
My luxmeter (as hardly any is) is precisely correct at 660nm, so the lumen numbers are correct and do provide a good measure of visual brightness. It maxes out at 4A with 320 lumen.
(That is extremely good output and efficiency, given that the perceived brightness at 660nm (photo-red) is six times less as 625nm (most common red leds) link . So with the same radiometric power a 625nm led would put out 1900 lumen, a green led even 5000 lumen).
So if the 660nm SST-20 has similar updated technology as the XP-G3 it should perform very well.