Sorry, I've been out of the VW and TDI world for a few years now, so I guess I need to brush up on my info. In any case, redline on the newer TDIs is actually 5,100 RPM and I think it was 4,800 RPM on the '09 TDIs. What it was prior to that (non-CRD TDIs), I forget, though 4400 RPM seems to jump out at me. Anyway, with a 5,200 RPM redline (per Mazda's website), the new Mazda diesel still isn't an unusually high revver.
What does fascinate me about the new Mazda is that it has an unusually low CR, and it meets emissions standards without all the fancy NOx aftertreatments.