There are some studies of the 'Anointing' which discern between our souls being filled with the Spirit and the Indwelling of the Spirit. The Indwelling being a permanent state with believers in the Church Age, and non-experiential, while the filling of the Spirit might be experienced in as many different ways as there are different gifts of the Spirit.
This perspective nicely accounts for the Sovereignty of God in the regeneration of the spirit and perceives the atonement of Christ being unlimited. One saved, always saved perspective, but discernible from a contuous filling of the Spirit. An alternate perspective tries to rationalize the effects of post-salvation sin as evidence of one not having been saved or losing one's salvation. (Both of which I assert are heretical.)
Of course, as long as we place our faith in Him in all things after keeping our accounts short with Him regarding our known and unknown sins, it's rather a moot point as to which we refer because then He is free to indwell and fill us with His Spirit.
Thank you for that .. you speak more eloquently than I .. *smile*