One thing to keep in mind is that if you are working with true type fonts that they will not always look crisp on screen, but they will print to the highest resolution of the printer because they are vectors deep down at their core. Unless you rasterize them, they will scale nicely but not always display correctly. This is true to a degree of other font types, but they take a little more knowledge of the formatting.
Often if you bump your dpi up too high you will get a muddier picture. This is more of an issue with screen printing, but I've seen it happen with desktop printers too. Also, if you bump up too high the file size can get out of hand on larger images (or if you go nuts with the dpi). This will cause the spooling not to work correctly or go unbearably slowly without any added visual benefit.
300 dpi like you're suggesting mr. keeper sir, should be fine, but about the most I would try on an injet. You might go a tad higher on a laser or dyesub if your source warrented it. I just like to point out that caveat since people always seem to think that more is always better. A lot of times they'll hear someone knowledgable tell them to "increase the resolution" and think "okay, lets try 2000dpi". Man if I had a dime for every time... hehe anyway. I like to stay in the 150-250 range for most desktop inkjet printing, unless you're working with specialty photo gloss paper, then I might jump up to 300-350. Most inkjet printers only have a linescreen of like 85.
One other thing that would impact this specific document that I thought about while I was typing this
is that it's got a dark gradient and dark type. So the antialiasing has less gradiation to move through to try to smooth things. That plus the thin serif font are probably just making some visual mud. Just for argument's sake, try looking at those fonts over a white background. Just disable the visibility of the gradient layer and see if they look any clearer. Just a thought.
BLURY FONTS 
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Linear Mode
