Not to get involved in the fun & games you guys are having, but I wanted to toss an anecdote in...
I tried, a couple of times, to inject sparring, in a real sense, into my aikido school/curriculum. My student's didn't care for it. I mean, I'd been at the TKD school recently enough and had some kid ask if I wanted to spar, and I asked him if he only wanted to TKD spar since my own game was rusty with disuse, but I could "do other stuff" if he was cool with it. He was, just asking me to "not break anything," to which I said, "It's much more likely just to be frustrating to one of us and that person will probably fall down more than be bruised."
So, we did. Kid was pretty good, strong, quick and explosive kicks, agile in that way I vaguely remember being, myself. LOL! I did prove something to myself again, that the mind keeps track of things even when the body is going in the ditch, fitness-speaking. It was fun. He went head-hunting, which I gently disabused him was going to be easy with a couple simple rising deflections, taking his balance off of the support leg in a manner totally illegal to my experience in typical TKD sparring... unless I've missed a rules change recently. As he'd be correccting his balance, I'd have done something like an arm drag, or circle step while linked to him to get to his back.... a few times until he caught the timing of it I had him in standing hadakajime (rear naked). He got that part figured out, so I change it up on him again. He was touch-tapping me some... but I was staying a bit farther away from him than he was used to, until he'd overextend and I could close. Sometimes to judo distance. I loaded him on a couple things but didn't throw. It was a good time. Was he going 100%, of course not. Was I, again... of course not. Did I learn much... well, not really, as I'd learned most of what I'd used back in my own TKD days and was just applying that knowledge differently. But... did he? Of course. At least, I think he did. Maybe he just put me down as "a cheater" and went about his day.
But, I never did get my own aikido class folks to buy intot he idea. I think it's actually "because" of the name, aikido. Preconceptions are used to decide "what we want to do" as much as "what we are doing." I finally gave it up.
Though, I'd still mess around with other school's guys if asked at their places. If it wasn't a Rambo gym where'd I'd get on the mat to learn and share and someone would try to pull my arms off or very seriously try to poke me in the eye. I've only got the one working eye, so my built-in redundancy went away.
All right, go back to the efficacy discussion...