Today,
ocicat and I have been posting similar information, as we are writing comments simultaneously.
Neither of us use M:Tier's services, but we think they should be investigated if building the system from source per FAQ 5 or release(8) seems confusing, complicated, or difficult.
FAQ 15 doesn't provide step-by-step instructions for comparing interlocking run dependencies in the ports tree against the installed package database, and the building the resulting required package set. This may be another reason to investigate M:Tier's services.
Generally, -current users should have the knowledge and skills needed to manage the development branch beyond installation and upgrade. In those instances where the admin doesn't have this but -current is an operational requirement, the astute admin takes steps to mitigate risk. This might be backup and disaster recovery procedures, commercial support agreements, or the admin taking steps to obtain required knowledge and skill through education and training. Or a combination of these.