The N950 has a less powerful vibration motor than the N9, resulting in barely felt haptic effects. So I opened the ivt files with MOTIV Studio (downloaded from here) and ramped up the values a bit. Where the values were already to the max, I upped the duration a bit. The result is a less refined but stronger haptic experience on the N950. I believe it is better than the Harmattan Beta values which are just a flat vibration.

Thanks to arcean for pointing to the files that need to be edited.
P.S. If you want stronger haptics on your N9 you could try this also, it should work.

Unzip the attachment and replace /usr/share/themes/base/meegotouch/feedbacks folder with it's contents, and reboot.