I would avoid the Sony PCM-R300 unless you get an amazing deal. I have one, and while I love it, I had to get the transport modified earlier this year due to it having some model specific issues. Cost me a ~$200 to get it done at Pro-Digi. Unit works great now, and Paul told me it should last well beyone my DAT taping, so I am happy. But this is something you should consider with regards to getting a new one.
Nick