I can’t say much to docker in LXC as I’m not using it, I vaguely remember some limitation I’ve read of but if it works fine for you those don’t seem to apply.

A VM has more overhead than an LXC, but with several LXCs maybe a single VM wins on overhead.

I currently have most Docker containers in one VM and am thinking about splitting it, the main reason is that 2 deployments have way larger volumes than the rest. This leads to the snapshots of the VM being very large as well and if I would need to restore from snapshots for a “small” application, it would take super long because of the large ones.

A single VM may be a bit easier on maintenance than several LXCs.

If you don’t have a specific reason to switch, I would not.