I agree with the comments about nikajo. I'm learning both ways, with and without pain. The best controls are on my center, through the joints, not on the joints. Makes a world of difference. Its interesting how some will automatically go to the shoulder control (uke's wrist against nage/shite's shoulder) when they fail initially to control the center. But this version really relies on pain and power for the control, and if there is any loss of posture on the part of shite, it is rife for opportunities for reversal (espcially sacrifice throws). There is an interesting article on aikido journal somewhere that speaks to this...I'll try to find it and post it.
I think the throws that make me most nervous are kubenage and varients of ganseki otoshi.