Having a mixture of credit types--Revolving, Installment & Mortgage--is good for your credit if they are paid as agreed.  Having only one type, especially if it is revolving, is not a good thing for your credit score unless they are all paid as agreed and do not have more than 50% aggregate usage.  A mortgage loan being paid as agreed is the best type of credit to have reporting, because it is usually for a higher dollar amount and if handled responsibly, will be a good indicator to future creditors as to how new extensions of credit will be handled.

On the other hand, a missed mortgage payment will have a larger negative effect on your credit and will magnify other late payments [30 days late or more] and their cumulative effect on your credit scores.