I find aiikido is as hard, if not harder on my joints and body than BJJ is. IMHO, aikido is a perfect complement to BJJ. In fact, the softer nature of it that teaches the principles is a wonderful fit.
Find a good Sensei and give it some time. AIkido as practiced by most (not all!) is a principle oriented art, not so much concerned with the "SU" skills as the "DO" side of thing. So by nature, you will probably be slightly frustrated at the different approach most take to it.
You asked some honest questions so I won't preach my two cents worth
BUUUT I tend to agree with Young-In park.
BTW, I am a MMA, BJJ guy that is in the U.S. Army and find the "soft" side of aikido very applicable. In fact I am teaching my soldiers tommorrow!
I start out with some warm ups, we do about 20 minutes of pure aikido work, then transition to MT type strikes for mid-range training, followed by pure BJJ ground work, then back to aikido (suriwaza) and Kokyu tanden ho, for a cool down.
I consider it MMA, but aikido is the base of what we do.