What Turntable to buy under $600 ?

I offer the third vote for a used Rega P3. But I disagree strongly that the RB 300 is a "pedestrian" arm. In fact, considering its price range, it is just the opposite.

"I've been planning on buying a Dynavector 17D MKII (one of two classic cartridges remaining I want for my collection...)"

Johnnantais, DON'T DO IT. This thing lasted less than an hour on my table - it was truly awful. This is the castrati of cartridges - absolutely and utterly lacking in bass. I have absolutely no idea what reviewers have heard in this cartridge that they liked. You will notice that there are a lot of these that appear for sale with 5 hours or less on them. There is a reason.

Well, perhaps I should qualify my invective against the Karat 17D just a little. My system includes JM Labs Electra 926s, and bass is not the strong suit of these otherwise admirable speakers. Also, my Linn equipment is very detailed, but not the most dynamic. So the bass-light, detail heavy 17D probably had no real chance of synergistic success in my system to begin with. But you should also know that several people I have run across have commented on the poor bass in this cartridge. In my system, it sounded worse than poor – it was like my woofers had disappeared. As to burn in, well, I am sure it can make a difference, but I personally don’t know how much. (I didn’t want to listen to it for the requisite hours needed, and also, it was easier to sell with only an hour on it.) If you do buy one of these, I'd advise picking one up used. I have seen them several times with very few hours for considerably less than half of what they cost new.