Re: aikido vs jiu-jitsu
Well whoever said "knee him in the face" while attempting a takedown has not obviosly nevere ever wretled a good wrestler.
About biting and pinching - have you ever thought about what would happen if they started biting or pinching from the top? Or eyepoking? Of course one does not expect that you pinch them from the bottom because it's a training situation. But in self-defence when you are mounted and someone is bashing your face up and adrenaline is flowing I'm 99% sure that your pinching and biting will fail.
If you are concerned with BJJ, take BJJ yes. It would be totally unrational to start figuring out some "aikido-counters" half of which would never-ever work and the other half you would train with people who do not know how to do the moves properly you would want to counter. So you'd be still in trouble with real BJJ.
A while ago Jason DeLucia posted some ancient bookscans of Aikido master showing full guard, armbar (a quite crappy one btw) etc to prove that Aikido has groundfighting too. But that is not the point. Groundfighting has evolved major leaps from the time it was practiced maybe by some Aikido masters as well. So my point remains, if you are concerned with BJJ - learn it. It's fun too. If you are not too troubled and have fun doing Aikido - then devote yourself to Aikido.
I usually teach 20 minutes of groundfighting almost every Aikido class. Simple escapes (with and without punches) and sweeps and some locks maybe. Also maintaining control after doing a throw. I think it is beneficial and necessary to have at least SOME groundfighting experience from SD perspective.
Also I have had experience in Aikido seminars with dorks who would try to drag me down (totally cluelessly) after for example iriminage and claim that "i did the technique wrong". Now I'd be glad to go and put knee on stomach on them and do an armbar.
Okay that sounded a bit arrogant I guess... I think there's nothing wrong in rationally pointing out and helping out someone with the technique but I really hated it when a guy dragged me forcefully on top of him in training situation and then started claiming and teaching how I did wrong and he could throw me (yes on top of him) at the same time being totally clueless about throwing and groundfighting.