Hi Brian, as a seller of both roll bars, first, I am looking for your opinion on the differences of these two products as there is a fair difference on the price but there does not appear to be much difference in their product descriptions and available photos. I am assuming that there are no full photos for commercial-in-confidence reasons to limit copies of their product. From what I can see, both appear to have additional side braces that are secured somewhere around each rear wheel well to effectively provide a 6 point mount and the Fabworx has a lower cross diagonal brace that interferes with the centre glovebox but clearly provides additional torsional strength.
Second. On the Miata.net forum, Moti mentions that utilising a 4 point harness with the factory seats for track work is a no no. As an absolute beginner, I don't understand how this is not safer than the factory 3 point seat belt and the same factory seat, particularly for a road car that may do half a dozen track days a year. In Australia to get a dual purpose seat that satisfies both track work and meets legal road rule requirements (reclineable) with the side airbag, lands you at around $4000AUS for a Recaro seat (a huge investment for 6 track days a year and still without a roll bar).
Third. Again sticking with Moti, he stated that a double loop roll bar is not in the same league as a standard roll bar design and I am inclined to agree, but I would contend that a double loop bolt-on set up that replaces the two factory hoops and including the side braces and an integral harness bar with about 65mm additional height for extra broomstick clearance that still fits under the roof and with a 4 point harness, is a lot safer than the standard set-up and far more cost effective for the 99% road, 1% track car. Please consider that this statement is from an absolute beginner looking for answers and working to a budget!