Hi Yaron,
Performance of BPC on HANA doesn't depend on number of Dimensions as much as performance of BPC on "old" data bases. Also, HANA doesn't have restriction of 13 customer Dimensions in a cube.
Size of Dimension definitely affects performance, but by how much depends on the data processing you made. You can look at it this way. Data processing has 3 parts: read, calculate, write.
Now, read time will increase only logarithmically. Write time will increase linearly. How calculation time will be affected depends of what type of calculations you make.
Just to clarify - those estimates are based on number of records in the cube, not size of the Dimension. I.e. if you increase your Dimension 100 times does your cube size increase 100 times as well?
Regards,
Gersh