I needed to cut some fairly messy material last week. I can get to maybe 80% of the machine to clean it. However, access to the fan is very limited and it’s difficult to clean. I found that a 1" chip brush was able to get through the grill to the fan and having the hose for the vacuum right there got a fair bit of the gack off the fan. That being said though, I can’t get to the cable track to clean it. I can see that this will be a huge issue down the line. I’d love to know if you have any way to get into the sides of the machine for cleaning? Several of the large machines I’ve used have had baffles that tracked with the gantry (front and back sides) to minimize the mess on all the important stuff outside the cutting area. Is this something you might be able to add at some point? I’m not expecting it on this version, but if you update your design, it might be worth considering.
Personally, I wouldn’t worry about it too much, the residue is a super-fine particulate, essentially ash.
Unless you are cutting something like travertine or Corian, I seriously doubt there is much of an abrasive quality to it.
Then again, I have a much higher threshold to filth than most… 
I’m mostly concerned because mdf, whether proofgrade or not, is basically sawdust and glue. That has to be an issue over time if you cut enough of it.
Having electronics in the cutting volume worries me. If there is any carbon left in the ash it could be conductive.
The grill over the exhaust exit seems excessive. The only purpose I can see is to guard fingers but in normal use it is covered by the duct. A more conventional wire fan guard would work better because it is far more open and smooth and rounded so less likely to catch gunk and easier to clean.
I somewhat worry as well…i clean it every week and always get me that I can’t get to that fan. I wrote earlier I think when we send it in for bulb replacement they would offer a type of glowforge forgewash!! I’d even pay extra for them to clean the fan for me while they have it open.
Thanks for the suggestion! I’m going to send it to our product team with a note that it came from a customer request.