I hate this too they make a new version than they take steps backwords..
anyway here is my idea keep a working copy of 6.5 on your computer I have this always in case of bugs in new versions the way you do that is before upgrading to 7 you go to applications duplicate the application in the application folder… rename it to finalcut 6.0 or something so it doesnt update it when you update the the 7 one
next open fcp 6 do the speed paste atrributes after cutting than make a copy of the project and open it in fcp 7.0 and it would have your speed changes on all the clips