I, too, thoroughly enjoy reading these articles about super fast debt repayment! I actually do something sort of similar but less extreme where I write down my student loan principal balance after each payment. Seeing the principal go down each time I pay gives me a thrill.
I would argue that some debt is worse than other debts only in that some debts (looking at you, credit card debt!) compound more frequently than other debts and at way higher interest rates. Most credit cards compound DAILY at exorbitant rates, whereas, a mortgage may compound monthly or my SallieMae loan that compounds daily as well (but with an APR that is approximately 15 percentage points lower than my credit card). Food for thought.