Yes, Death on the Reik is part of The Enemy Within campaign (the best one, IMO). The prelude with Mistaken Identity is a great starting point for the campaign, and Shadows over Bogenhafen resembles Cthulhu adventures a lot without the unbeatable monster at the end (the worst part of Chaosium modules). Death on the Reik, a masterpiece: my players had four 6-hours sessions shipping idly up and down the Reik just for commercila purposes and minor adventures. You can keep control on its pace. Power behind the Throne has an overall nifty plot, although waiting for several milestones in the investigation can become cumbersome, unless you use Middenheim, City of The White Wolf to add spice. Something's rotten in Kislev doesn't seem to me as crappy as many people say; it, however, has not much sense into the campaign. Finally, The Empire in Flames is the typical end for an epic campaign. One of the best campaigns I have ever read and GMed.
Another "gem" could be Castle Drachenfels, a high-level dungeon (though your players would see it has been revamped once and more). Maybe you enjoy The Doomstones campaing despite its more classic fantasy tone.
