Oh BTW, I found that the later Lumagen scalers had a better comb filter than the Entech, you may want to borrow one if you can for comparison. Get a copy of the Video Essentials laserdisc and use the moving Snell & Willcox test pattern to ascertain how well your comb filter is working. Yep the BNC is the best output from the X0, as long as you are using an outboard comb filter.
If you have an oscilloscope, waveform monitor and vectorscope, you can buy the Pioneer LD test disc and check your alignment, levels, clock function etc. to ensure your X0 is running at peak performance.
http://parts.pioneerelectronics.com/part.asp?productNum=GGV1069