Some planes rock,some dont. Ive seen Caps and Extras that lock in and never rock, like a foamy. Even if you never did a harrier planes like that make it easy to do,too easy. Sounds like to me you got used to the way the Cap harriers and the Yak needs something. I myself have never had a plane that didnt rock some,the best was EF Yak(68" wing),it did rock but so gently you could ignore it,I chose to correct it with right aileron. I would hit right ail just as the right wing tip was about to come up, this would stop the rock for a few seconds,the more wind,the more often you need correction. I would try the Yak in the least wind possible,in the AM or PM,get it down in light winds first,then you'll have it down when its not optimum conditions. You might even need full right ail or continuous ail,what ever it needs. I used to hold full right aileron at times,being in HA,it never snapped out on me,just enough authority in that attitude to correct the rock,if you drop the nose suddenly,then it could be a problem. On the other side,if you were lucky enough to have a plane that doesnt rock,keep it.