One thing to keep in mind with all of the Denons is that Denon publish compliance figures measured at 100Hz.  The standard measurement used in resonance calcs (and issued by almost everyone else) are at 10Hz.  That means that the "real" compliance figures are going to be higher.

Put another way Denon cartridges aren't as low compliance as a lot of people think they are and so are suitable for rather lighter arms than many might assume.

I've only ever had a chance to actually test is a DL-160 on an RB250, but using an HFN test record, it would appear to have a compliance of 16 to 18µm/mN as against the published figure of 10µm/mN.  Which with its mass incidentally makes it an ideal match to an RB250.

PS. I wouldn't have called any of the Regas low mass .. medium mass definitely.