Thanks for the replies! I just handed in the report (hence the late reply), and they helped a lot while forming my discussion. It’s also helping me to get in the right headspace for my defense in mid-Sept.
Lmo:
Do you know a specific manufacturer that says that? The ones I found for reference actually recommended to keep the flue gases hot (between 300 and 500 F) to limit creosote buildup in the first place. I don’t think this is a realistic recommendation however, as we had trouble keeping the fire hot enough (I designed the prototype to have appropriate draft at this temperature, and backdrafting occurred in cooler periods).
Near the start of the project, I got contact info for a guy who specializes in predicting tar output from combustion, but he was on sabbatical, so that was a problem that I was hoping the testing would shed some light on. Now that the project’s over and I was restricted to using lumber, I’m kind of at a loss for an answer. If the accumulation doesn’t restrict operation over the course of 2 or 3 years of use (recommended chimney cleaning is once a year, adding in a safety factor), I think it’ll be fine. If it would, then something has to be done to prevent or clean it, but for that I need to know a lot more about the tar properties (does it stick to fibreglass? what’s the average viscosity as it hits the filter? is there anything that can be done to force it to become brittle? etc.), too many questions to answer with more pressing projects in the pipeline unfortunately… 
Scott:
I’m not sure if you mean the disassembly, or reaching the roof, so I’ll answer both:
The filter “cartridge” is just the rippled fibreglass, sealed on either side to an “O” cut out of stainless steel. Both the chimney attachment and the cap have an angled edge, and they all just press fit together. It’ll definitely be a problem with wind, but with access to more manufacturing methods, I’d like to make the attachment a quick release.
For reaching the roof, chimney cleaners have to access both the top and bottom of the chimney, so they’re up on the roof anyway. There would have to be some kind of partnership to ensure that chimney cleaners start offering filter replacement and cleaning services as an add-on. Assuming that is possible, the intent was to keep the life to about 2 or 3 years, to account for people not getting them cleaned often enough (recommended is once a year). The prototype was designed with no self-cleaning mechanism to get an idea of how much soot accumulates per burn, and determine if self-cleaning mechanisms are necessary, and to what level.