I agree with BKaspars, you should not be considering an upgrade to DP 8 at this time, as it has had more of its share of 'challenges'
However, I do think that you need to consider upgrading to DP 6.2/6.21 or 7.0/7.01 which have direct upgrade paths from 6.10, and don't involve a major revamping of the IDB. As you are probably aware, neither 6.10 or 6.11 are currently supported, and, if you needed to open a case, you may be turned away with an unsupported release
I hate to have you plow through more documentation, but these directly describe the Upgrade process
Installation and Licensing Guide for DP 6.20
Chapter 4
INstallation and Licensing GUide for DP 7.0
Chapter 4
No matter which version, I advise that after installing the release, you install the patch bundle which wil get you to either 6.21 or 7.01