I will declare my bias up front. I learn aikido and teach karate and I was older than you when I started aikido. Both are great martial arts and the softness that you talk about trying to find in combat Tai Chi also is the basis of aikido. The downside is the time it takes to become reasonably skilled in aikido. What I would suggest is to go to the karate school and see if you can take part in a lesson. (Personally I give potential students four free lessons to let them see if what we do suits them.) Even if they charge you you will get a much better feel for what they do.
Good luck.
Good luck.
