Without wishing to open that can of worms - there are some very good technical experts on here who will tell you that a really well implemented SE output is as good or better than an average balanced out - I have found that the balanced out on the CDM or my Onkyo DP-X1 or my Glove A1 (paired with an "old" AK120) gives a wider soundstage, which I happen to like. So I would say that's the main thing that my ears (brain) pick up, rather than an improvement in sound quality per se. (The Onkyo balanced out is widely agreed to be quite a lot better but that's more a reflection of the average-at-best SE output rather than the balanced out being stunning, but I definitely notice the same difference with the CDM.)
To answer your question directly: yes I think it's worth investing in a balanced IEM (in my case) cable.
PS I use a digital micro USB - OTG USB interconnect to connect the Onkyo (or even my iPhone 6) to the CDM, so I am using the DAC and amp capabilities of the CDM. The iPhone sounded amazing that way with the CDM's balanced out as well. One thing I would say is that the most recent balanced IEM cable I bought sounds at least as good, or better than the CDM straight out of the balanced out on the Onkyo, so there is something to be said for getting a good DAP with balanced out for portable, on-the-move use and leaving the CDM for occasional listening at home.