Hi, budtech,
I'm not Bob, but I do own an Opticbook 3600 (not the plus) and have used it for a few years now. It works very well, especially in conjunction with the included software. Note that the non-plus version does not come with the scan-to-PDF software so I can't speak to that, but the software that is included with the standard 3600 works very well. I've had no problems at all that weren't operator error.
Since I prefer to do my own compiling, I scan to .tiff, then use Acrobat to put it all together and OCR it. That's just my work-flow and I'm happy with it.
I believe the differences between the models of 3600 are what software is included. The machines themselves all look the same to me, but that's opinion, not hard fact. There may be more indepth information on Plustek's website.