The Plustek scanners have had poor reviews compared to the ScanSnap series. They don't seem to hold up very long. This particular one seems to be in short supply which suggests it is either very new or has gone out of production. I wasn't able to find any reviews on it either when I did a quick search.
The ScanSnap s1300 has recieved good reviews. Keep in mind, this is a portable device. It's slower than the s1500 and the paper tray holds only 10 documents compared to the 50 of the s1500. It probably isn't designed to handle as much volume in its lifetime as the s1500. I have a s1500 and have been very pleased with it. The only caution I would have for the s1500 is to keep it clean. Use a vacuum to get rid of paper dust, never compressed air or even just blowing on it. I had to send mine in, fortunately under warranty, to get rid of paper dust that worked its way into the non-consumer accessable portions inside. They recommended using a vacuum, which I do now, and haven't had any problems since. Customer service with Fujitsu was excellent.
If all you do is scan an occasional 10-50 page manual, the s1300 would probably meet your needs. Of course, there is the danger that you will get hooked on scanning every piece of paper that comes into your life and regret not getting the s1500.
