Having worked in an industrial steel laser cutting shop for over 5 years, I can attest to the nasty stuff these things create. Now, we're talking a different order of magnitude as far as power goes (5000W vs. your 50W) but the concepts are the same. When cutting steel, the majority of the by-product is extremely fine iron oxide dust. The best way this was handled was through a huge multi-filter "bag house" dust collector and down-draft cutting tables.
I suspect though that your case will be a bit different since you won't be cutting thick steel with 50W. Smoke from oils, plastics and glues will be your biggest problem. The dust collector probably didn't capture these things but the downdraft tables got it away from your lungs most of the time. Although routing your exhaust outside may be a real pain, I suggest that it will be money and time very well spent. Just like when you buy a mill or lathe, the cost of the machine is only a portion of the total cost. There's tooling, upkeep, repair, etc. Have you researched what consumables these use and the cost?
Think of everything as a package - your laser and accessories to ensure your health and those that live with you.
Oh, and on a related note: I have no experience with the small lasers, but the industrial machines I've worked with sure are finicky beasts. I suspect the same will be true or worse for the small ones.
