^^I agreee with that definition, but it is quite broad.
Is Jungle only defined by the beat tempo and structure? maybe, but is there not some other boundary that contains all DnB styles...maybe not? Is it possible to come to a more exact definition without eliminating enything that is DnB.
The other problem with that definition is that while it is by and large the case, there are tunes which have slower (or faster) bpms and occasionally straight beat bits for a portion. (ShyFX feel good being the most recent example, Blame's endeavours in different time signatures, some older tunes go into hardcore type beats, one of the mutationz remixes slows down to 140ish bpm for the last minute....)
for all encompassingness, i think thats an agreeable definition though