Would it be fair to say something like, The Enemy Inside = Constant Motion = As I Am = A Rite Of Passage = Pull Me Under = Panic Attack = On The Backs Of Angels? (I'd almost say Honor Thy Father, but that one's sorta different somehow, and As I Am kind of fits the bill just a little bit more. Same with Build Me Up Break Me Down, it has all the bits and pieces, it's problem is that OTBOA exists). I'm not just listing singles here, it's just all of these songs seem to serve a similar purpose on the album they originate from. I believe the other albums have a candidate for this idea but it gets more convoluted and subjective to include them all.
But DT songs can definitely be categorised into multiple different categories depending on your definition, so nothing is set. Although to me, The Enemy Inside is the 'hard rocker' by default, essentially the opening track (after an intro), being used as a set opener live, was released as the single. It's non stop energetic. It does actually have a few more elements than the 'hard rockers' of the past but I think it primarily takes this role on the new album. I be careful not to use the word 'heavy' because even though TEI is certainly a heavy song, the tone and technique style plays a huge part in determining if it's 'hard' or 'heavy' (but I'll avoid getting into attempts to describe abstract sounds with common words that can't properly define these ideas, they can only symbolise them).
Because as someone mentioned, Enigma Machine is arguably 'heavier' than The Enemy Inside. And the other songs on DT12 seem to represent multiple DT styles.
Considering all that though, it still feels like another 'hard rocker' (for lack of better simple description) would've been nice on DT12 but that's just me. There's more than enough content in the other songs to be happy and I can't expect DT to tred the same ground twice just for the sake of it, but all the songs mentioned at the beginning of this post, I think DT need to make more in the style of.
They're really good at making these songs, but I always think they hold back and only write about 1 every album cycle, trying and stick to their proggy roots which tends to lean away from these 'harder' songs. BUT it absolutely doesn't have to.
Then again they're also good doing 'epicly big' sounding songs, but still structured to a formula (like The Bigger Picture, which for serious lack of a better word is almost a ballad, but it's too HUGE to be considered as such in the traditional sense). And they've been pulling that off pretty well lately (Breaking All Illusions/Bridges In The Sky/Behind The Veil etc.)