$300 to $350 is, in my opinion, a good deal on a good condition 5903. The 5903 has an aluminum alloy receiver, as opposed to the stainless steel receiver on the 5906. It is lighter in weight than the 5906, making it easier to carry. Other than that, it is the same as a 5906. These pistols tend to be incredibly reliable, so long as the recoil spring is replaced every 4000-5000 rounds. Accuracy does vary, some very accurate, others combat accurate as these were not intended to be target pistols. Recoil will be slightly greater with the lightweight 5903, but it is still easily managed. The only other thing I can say is that a 5903 is not likely to be as durable as a 5906. If you are planning on shooting 500 rounds a month, you would be better off with a 5906. If you plan to shoot 500 rounds a year, the 5903 may outlast you.