GTD is a tool and can be used for any goal
I am or have been a workaholic, too. When I found GTD I first did it for about 6 months and got much more organized. However, I somehow felt that I was doing it for wrong reasons, trying to please everyone, it was no helping me to say no to things not meaningful to me. I could see that I did GTD in order to do MORE when an inner voice was telling me that doing less would be the only answer.
So I set GTD aside, decided to come back to it, but only when I would take this tool and use it FOR me, not AGAINST myself. How would I know... can´t say, intuition I guess. I started again another 6 months later and set up a new system ONLY for personal matters. I have worked so much and so long that I was much more systematic and organized at work anyway, now I would not let myself use this tool there, but force myself to turn my focus to myself, family and friends by including ONLY personal matters. (That was in the summer, now that the home system if flowing nicely I´m starting to include work stuff in a separate system in the office.)
Soon after that I started doing weekly reviews WEEKLY. Just for one hour, not doing everything but whatever I could in one hour. I can never thank Kelly enough for the October WR challenge (Connect forum), it changed my life! The WR became the moment to REALISTICALLY pick the actions I really, really wanted to and had to get done in my personal life that week, all else went to someday/maybe and it was OK because I knew that if I ever "ran out of" next actions during the week (never did...), I could always go there for more and in any case someday/maybe would be reviewed next week.
After the Year End Review webinar (Connect) I realized that my 2011 focus is very much on shifting from work to personal and with my brand new Sleep Project I have now realized that you ALWAYS, ALWAYS do what you consider important, whether you are conscious about it or not. When sleep became a REAL priority I AM able to get to sleep earlier. "Go to bed" is just as important NA on my lists as any other and this is a high priority project now.
If getting MORE things done really is your goal, GTD will help you. But there is a limit to doing, we are human and if we try to do EVERYTHING there's a point when it doesn´t make us happier and sometimes the only solution is to learn to say no to more things. GTD will help you in that, too, but only if you really WANT to say no to more doing.
Recovering from workaholism, just like from alcoholism, has a first step you can´t bypass: admitting that you have a problem. When you do, GTD will help you transform that problem into a project and solve it. If you don´t admit your problem, GTD will be like a very sharp knife in your hands, but instead of opening a way for you through the jungle of your problems, it will cut YOU, if used for the wrong reasons.
Only YOU can know what are the right reasons for doing GTD.