I use electric fences all the time, but wouldnt use them too near roads etc. I find three strands of wire works best, you can forget the flat white tape, it doesn't seem to give enough of a shock.
Never used flexinet for much other than repairing holes in fences as a temporary thing whilst I'm waiting for the landowner to fix them. Flexinet (unelectrified) is good for guiding sheep into a pen or blocking off driveways etc when walking them from one field to another.