We have been using gold hog matting for the last 2-3 years, and have no problems with it. Works well on fine and chunky gold, but it can take a bit of playing to get water flow and velocity right, so the matting stays active. Once dialled in its easy to use a clinometer or bubble to make sure you get it back in the same spot.
Our main reason for changing over was mainly to reduce concentrates at the end of the day and speed up our cleanouts. Personally I don't think we get any more, or less gold from when we had the riffles and miners moss setup.
The mats are not cheap, so I would be inclined to try and have a look at someone else who is using it first, to make sure it is what you want. We had been looking at the mats for a while but was not until we saw them working that we spent money on them.
As AR mentioned some people have had problems cutting and joining their mats, so long as you measure twice and have a sharp razor and a good straight edge, I don't think this should be too much problem. I have even cut superglued pieces apart off and older mat and reused them (though I wrecked as much as I saved), as well as spliced two offcuts together to make a mat that I was short.
As for taping the mats together, I would follow docs instructions there. We have always used the tape on the sides, which helps to seal any gaps that may be between the sluice box and matting.
