I added the gradual turbo ramp down as a compile time option (TURBO_RAMP_DOWN) to both STAR and STAR_off_time.
https://github.com/JCapSolutions/blf-firmware
Instead of having a predefined mode to step down to, you define a MODE_TURBO_LOW PWM level. You can still have it the same as MODE_HIGH if you'd like, or just skip the high mode altogether. I got rid of the whole MODE_HIGH_W_TURBO thing while I was at it. Because the WDT was set to 500 ms previously, and because the turbo ramps down only 1 PWM level per "tick" (WDT timeout), going from 255 to 140 would take almost a minute. Instead of stepping down by 1 output level you could step down by 2. But I added another compile time option of TICKS_250MS, which will change the WDT ticks to 250 ms, so the turbo ramp down described above will take 30 seconds. Obviously tweak it however you want, but also realize that the "tick" timing affects the mode storage in the STAR program.
This addition was not applied to STAR_momentary and STAR_dual_switch. I would need to devote some time to making and testing the changes, so it might be a while until I get around to that (maybe when I actually get around to building a light with those UI's, because I've never used them).
EDIT: And please, as always, if you notice any bugs while attempting to use these let me know!