Question: "Would you confirm this globe will replace GE 18W F18DBX/827, F18DBXT4/SPX27?"
Answer: The key item to check for compatibility is the base type of the bulb. The Philips CorePro 6.5W we sell has a G24d-2 base.
From your picture, it looks to be this item, which is listed as having the same base type. If so, it is compatible.
Different base types prevent the wrong lamp from being plugged in. You can double check yours by looking at the lamp's base directly and comparing the position of notches and electrical pins against this diagram:
