I don't think it would be practical to put ZebraLight headlamps in a separate subforum.
Realistically, it looks as though the number of overall posts (not overall threads, but overall posts) in the Headlamps forum leans quite a bit toward ZebraLight due to heavy interest in those threads to which ZebraLight offerings are applicable.
However, the number of overall topics is still very diverse with a majority of threads that have nothing to do with ZebraLight headlamps at all (or recommendation threads in which ZebraLight is often included as part of the topic along with other brands). Those topics that do involve ZebraLight tend to develop into long threads because there is such interest in the brand, and often the top two or three topics are ZebraLight topics due to heavy posting which pushes them back to the top. But it looks to me as though 75 to 80 percent of thread titles have nothing to do with ZebraLight headlamps (at a quick glance).
Also...just to throw in a complication or two...how would recommendation threads be handled? For instance, where would a "Spark or Zebralight?" question be asked? Or, "Which One of These Three Headlamp for Camping?" if Zebralight was one of the candidates? You'd run into an awful lot of gray area and in many cases force interested folks to scan through two forums instead of one for threads of interest (or confuse folks about which forum they should post in...and to some degree make more work for moderators to keep things sorted).
I think the headlamps forum, from a practical standpoint, is best served as it is. Just my perspective (no disrespect intended for the question being asked).