We are still considering integration of Acronis backup but it was removed from the immediate roadmap based on customer feedback. The number of customers who would benefit from this feature is very small compared to some of the other things we are prioritising.
The built-in Enhance backups are incremental, they are extremely efficient, fast to create, fast to restore and integrated directly into the control panel. They require no additional software or licensing. If you are running mass hosting I would definitely recommend this method of backing up.
In addition we're building S3 as an alternative backup target - this is less efficient but it's ideal for smaller clusters (ie. managed/unmanaged dedicated customers) where a separate backup server would be excessive.