A lot of it depends on you and your circumstances.
For one, can you physically handle two full MA curriculums simultaneously? Usually, it is best to go to class at least four days a week in one art. Two arts with four classes per week means that, unless one of the dojangs is open on Sunday, you will have at least two days with double classes. Can you handle that?
For another, what kind of time do you have outside of professional and any family commitments? Each art can be a huge commitment in and of itself, and two together will be time consuming. Can you fit in class pretty much every day of the week and still meet your other commitments? If you do not have the time to devote to both the classes and to practice of the techniques, then regardless of anything else, it will not be productive.
Also, since you indicate that HKD woudl be at a different school, can you reasonably afford paying tuition at two schools?
Learning style is another factor. Not everyone can train in two arts with some common but differently executed techniques.
I train in both and teach one. I think that it can be done and can be done productively. But not everyone can do so or do so productively.
Usually, I feel that it is best to get a solid footing in one before taking on another. I had many years in taekwondo plus two years in a taekwondo class that had some hapkido derived SD techniques mixed in before I studied hapkido as a separate art. That was me. Some people can study two arts new to them at the same time and will thrive.
Welcome to MT!
Daniel
