Respectfully, I ask how you know for sure Aikido will keep you off the ground? I've trained in Aikido some (not extensively, but some), and although I see the merit in the style, I don't see it as a grappling defense answer. Nothing is a guarantee but an accomplished Aikidoist would be extremely difficult to get on the ground. Most grappling arts deal with one on one situations for the most part and not multiple attackers. Not for an accomplished Wrestler or Grappler. I haven't seen to many take down defenses in Aikido that I have done, and very little actual grappling, other than pin maneuvers. Aikido is very much a standup style, with a focus of joint locking and throwing. I was an accomplished grappler way back in HS. I have only studied Aikdo for a couple of years. Someone trying to get a hold of an accomplished Aikidosit to take him or her down is I for a surprise.