Using an init system means you get a more complete framework for managing system state, as the process of booting, configuring early minutiae like TTY and environment setup, shutting down and maintaining service groups in the form of runlevels/milestones/targets are handled.
systemd is a rather exceptional case as it's a project which aims to enforce standard policies and tools for just about the entire layer of low-level userspace. So you will be incurring significant workflow changes beyond supervising processes.
Depends on how far your needs go.