I'd like to use something similar to the Attribute transfer to add an attribute that I can use for smoke and particle emission. However I want to to stay and then fade after 24 frames. I could kind of create the effect with the trail sop but there are two problems. 1 I couldn't think of a way to have the trail copies fade over time. The other problem is that if the geometry that is receiving the attributes is moving then the trail method definitely won't work. Any ideas?

You'll have to use the solver, this page [www.tokeru.com] explains it very well, with a section on fade effects.

Of course there’s an answer on tokeru. I’ll check that out.