The H/K 7300 will likely produce more actual power output than the Denon. H/Ks tend to be conservatively rated. The previous model, the 7200, had massive measured power output, considerably higher than its conservative rating.
Denon tends to exaggerate somewhat on their power output, but they are reasonably close.
Check out the remotes as well. H/Ks in the past tend to be annoying--I got used to mine-- and some Denons have tiny buttons that are not intuitively arranged, but no remote is perfect. Maybe H/K has improved the remote.
HDCD has nothing to do with SACD or DVD-Audio. HDCD is a kind of compander circuit mixed with a lot of hokum. If it's there, fine, but do not make a buying decision based on the presence of HDCD.
SACD and DVD-Audio are "hi-resolution" audio formats that, in theory, and in measurements, are superb, but resulting multi-channel mixes are wildly variable (Neil Young in the rear channels? Ridiculous..) and it's anyone's guess whether either will succeed commercially. One might survive as a niche format, but only time will tell.
Axiom Resident Expert