IMHO, I would encourage you to take aikido. I am a hapkido practitioner also and did aikido before
my hapkido practice. I have the opportunity to practice aikido at a near by not-for-profit dojo who welcomes "occassional" students. Although there are many of the same or similar techniques/movements in hapkido the way they are executed, typically, are not as fluid as the aikido technique. For me, taking the occassional aikido class "smooths" out the same hapkido technique and adds a different dynamic to the whole thing. The size (big v. small) of the circles in executing the techniques accounts for much of the difference but there is more to it than that. I guess you'd have to take some classes to understand what I'm trying to say as it involves the " feel
" of it and that is almost impossible to convery here.
Give it a try. I think you'll be glad you did