If your hearing is good up top and you like a sharp presence to the treble then you will likely miss having a small tweeter with that driver. I ran the CDT ES-02 without 1" tweeters for quite some time and at high volume it just wasn't good enough for my tastes on the top end. The newest HD-2 is supposed to have a little more extension toward 19 kHz. The most common complaint people have about running a wide bandwidth driver like these is a lack of airyness and spaciousness. You can always add a small tweeter if you like. If they're anything like the ES-02 as a midrange they might make your jaw drop.
CDT has a new aluminum tweeter called HD-1A/bl that has a housing to match the HD-2/bl. I'm not sure it has shipped yet but it's for someone who wants the treble to pop. If that combination is anything like what I'm running with ES-02 and DRT-26A aluminum tweeters it's going to be amazing, especially at the lower price of the HD line.