Clarifications:
1) In the Somali I speak, dh has one and only one use e.g. baradho, dheere, qardho in contrast to words that use only d e.g. dee, diin. I found JugJug's explanation for the alternative waqooyi usage pretty interesting
2) Similarly, kh is perfectly pronounceable in the standard Mudug accent, although the non-standard q can sometimes be found in usage among ciyaalka xaafada.
3) I've found that most of the glaring differences in vocab are usually loanwords e.g. tuwaal/shukumaan, nigis (knickers)/kastuumo.
4) I would argue that there are quite a few accents in Somalia, from the waqooyi, mudug, xaayow, banadiri, elay, and a few others I'm probably forgetting or aren't aware of. I've never understood the ceeb measuring contests of Somalis; if anything, we should be celebrating the diversity and vitality of our language.