I wrote a reply, but lost it...so this one will be shorter :):
The fade message, it seems, does the same as normal float input OR the recall message. I wonder if there really is any added functionality?
I used lines to interpolate before, but their annoying input format, separate event generating and the inability to set the ramp time during a fade (middle input doesn't work at that time) made me use a (q)metro with a timer. This way, i can sync output independent of frame rate: