Summary: I haven't tried this unit in "real service" yet but did unbox it and did some speed testing. With two macintoshes (a Powerbook G4 running Tiger and a Macbook running Snow Leopard), I measured speeds using iperf, first using a direct CAT5 cable running between them, then with the pair of MCAB1001's connected together with a short piece of coax.
Summary: I read the reviews on here of other people saying it didn't work for them, and I bought it anyways hoping it would work for me, but it didn't. It seems like it's only set up to work for a specific setup, and if your setup deviates even a little, it won't work. I could never get the coax light to come on, after doing research on other forums and sites and trying their tech support, my best guess is that because I live in a condo and they amplify the cable right outside...
What You Need to Know About Why It May Not Work (but won't find out from reading the product details)
J. Crew, Amazon
2 September 2009
Summary: As others have mentioned, this product operates at 1.5 Ghz frequency. However, apparently many (most?) cable company-installed splitters and amplifiers top out at 1Ghz/1000Mhz. What this means is that if you have splitters and/or amplifiers in your line, this product may not work, since the frequency the network data is transmitted on between the Coax units may be filtered out by the splitters and amplifiers.