Both of them are going to be in demand in the future, it really depends on the size of the organisation you work for. Quite often the same dba does both, as well as designing and developing the database.

You really have to look at what you enjoy doing, if you say that doing production support is making your life miserable then maybe it is not for you.

Though i don't think it will hurt your career to do get some production support experience.

If you want to make a career out of being a development DBA then it would be good to learn about all aspects of software development and it wouldn't hurt to learn a specifc dev language like c# or vb.net

SQL careers can vary greatly and you should look at working the field that you enjoy or no matter how many £££ you make you will still be miserable.