ComboBox Linked Cell

Updating a displayed cell in code does have a cost, but only one combobox will be updated at a time and the update is done by a user, so the cost of updating a single cell is negligible. (When code updates a lot of cells all at once, there is a steep cost, which can be mitigated by turning off Application.ScreenUpdating.)

The benefit is, as you suggest, being able to use it in cell formulas. If you're not doing that, then no harm in removing the link.