I have a Janome 350E which is the same as the 300 but with the thread cutter. What would you like to know? I can't compare, but I can tell you what I have. I have two hoops-- the smaller hoop and the larger one (up to 5x7).
I like large designs, I think (at least it seems like I have that tendency), so I think if possible, get one with a larger hoop (at least up to 5x7) depending on your personality.
I bought mine used for about $670. New, they run about twice that here in Poland. I think you might be able to find them cheaper than that in the states, though.
I like having a separate sewing and embroidery machine.