Sluice matting is like any other equipment used in mining. You have to fit it to the terrain, or in this case the materials you're running.
That said, you should consider something that will give you the most bang for your buck. The more different types of recovery surfaces you can get in your sluice the better. Simple piece of carpet can recover gold, but if that's all you have in your box you will only have a single surface. If that surface won't catch certain sizes or shapes of gold at the top of the box, then there's very little chance that it will further down. If you add riffles or expanded metal you increase your chances of catching more gold that you would have missed.
As an example, I was running a long tom style of recirculating sluice out here in the desert but found that the carpets and riffles would get clogged up with black sands after only a bucket or so. Needless to say this was a pain because I had to stop and do a clean out way to often. Once your recovery surface gets clogged like that you end up "Flat boarding". There are no more nooks and crannies to catch the gold. I ended up breaking out my "Drop Riffle" sluice and that worked much better in THAT location.
While there are many different types of matting on the market, they are not all created equal. While some will work well with your materials, others may not be as effective. If you want to see what works best, you have to be willing to experiment a bit with different capture surfaces. Doc from Gold Hog offers several styles of mats that will join together seamlessly and offer many different catching surfaces all in one mat. They are a little on the pricey side but have become known to be some of the best gold catching mats on the market. Do your research before you buy and in the long run it will save you money.
