How to auto-detect a USB drive?

[Peter Steele]

> Last week I submitted a patch to get this system and subsystem 
>documented in the manual page of devd.conf. It should be in CURRENT now, 
>and will be MFC'd to STABLE in a week or so. 

This looks like exactly what we need, except we're using 7.0, and are too close to releasing 1.0 of our software to make a switch to 7.1 now (QA would want to run weeks of testing). 

What are the issues with devd and 7.0?