Does anyone know how frequently a DSSS system may change channels? At
some point it has to resemble a frequency hopping system enough that it
falls under the rules reguarding hybrid DSSS/FHSS systems.

47 CFR Part 15 section 15.247(g) does say that "a [hybrid]system
employing short transmission bursts must comply with the definition
of a frequency hopping system and must distribute its transmissions
over the minimum number of hopping channels
specified in this section. "

This seems to suggest at least that a bursty DSSS system that changes
channels must follow the rules for FH.

Can anyone out there clarify things?