Yes, actually, I can provide evidence for Paul's emphatic statement.
In Acts 19 we see an encounter with Paul and some believers in Ephesus. In that account we find that they had been baptized into Johns baptism, but not the Spirit. At that time Paul laid hands on them and they received the Spirit. It was a big deal to them.
So later, when we see Paul writing them a letter, he makes this emphatic statement to them(verse 13) concerning the Spirit. That's why he uses that 'word' that seems to indicate he was switching over. But in reality, he was trying to be very direct that they need to truly understand they do have the Spirit.
They knew the rest of it, what his introduction was about, and that's why he wasn't speaking to them in the 'you' perspective, but rather the 'us' and 'we' perspective. But reaching that one point, about the Spirit, it's like he wants to grab their attention. It's a literary device to direct the readers attention. We see just after that statement he goes back to using 'we' and 'us'. In chapter 2 verse 5, was he indicating that the 'we' and 'us' group were one thing and the 'you' group was another?
The whole point is moot if one just understands he begins the letter addressing them in the first place. It clearly states;
"Paul, an apostle of Christ Jesus by the will of God, To the saints who are in Ephesus, and are faithful in Christ Jesus:"
He clearly is addressing the saints in Ephesus who are faithful in Christ Jesus. One group of people. We see other writings when he clearly is addressing two different people, namely Philemon, and it's not the same kind of introduction. So why we would assume this introduction was meant for two different people should not be. None of the other letters to the churches as a whole ever had the indication that he was separating out two groups of people.
Here is an copy/paste from a interlinear Bible;
http://www.scripture4all.org/OnlineInterlinear/NTpdf/eph1.pdf
paulos paulos G3972 n_ Nom Sg m
PAUL
apostolos apostolos G652 n_ Nom Sg m
commissioner apostle
ihsou iEsou G2424 n_ Gen Sg m
OF-JESUS
cristou christou G5547 n_ Gen Sg m
ANOINTED Christ
dia dia G1223 Prep
THRU through
qelhmatos thelEmatos G2307 n_ Gen Sg n
WILL
qeou theou G2316 n_ Gen Sg m
OF-God
tois tois G3588 t_ Dat Pl m
to-THE
agiois hagiois G40 a_ Dat Pl m
HOLY-ones saints
tois tois G3588 t_ Dat Pl m
THE-ones the
ousin ousin G5607 vp Pres vxx Dat Pl m
BEING ones-being
en en G1722 Prep
IN
efesw ephesO G2181 n_ Dat Sg f
EPHESUS
kai kai G2532 Conj
AND
pistois pistois G4103 a_ Dat Pl m
to-BELIEVing(p)
to-believers
en en G1722 Prep
IN
cristw christO G5547 n_ Dat Sg m
ANOINTED Christ
ihsou iEsou G2424 n_ Dat Sg m
JESUS
Notice no defining of a difference between "the" ones being in Ephesus and to believers. "The" would make a distinction if there were two different groups of people. Instead, we see the use of the word "and" which means - also, are, etc. That word "and" connects the word "Ephesus" with the word "believers" - it quite distinctly brings them together to indicate they are the same person. Believers in Christ is descriptive of the Saints being in Ephesus.
Example; "My dear wife, who has lovely brown hair, and who has blue eyes". Now, I am speaking of the same woman, not one who is my wife with brown hair, and another woman who has blue eyes.
Here are his introductions in Biblical order;
To all those in Rome who are loved by God and called to be saints: Grace to you and peace from God our Father and the Lord Jesus Christ.
To the church of God that is in Corinth, to those sanctified in Christ Jesus, called to be saints together with all those who in every place call upon the name of our Lord Jesus Christ, both their Lord and ours:
Paul, an apostle of Christ Jesus by the will of God, and Timothy our brother, To the church of God that is at Corinth, with all the saints who are in the whole of Achaia:
Paul, an apostle-not from men nor through man, but through Jesus Christ and God the Father, who raised him from the dead-
and all the brothers who are with me, To the churches of Galatia:
Paul, an apostle of Christ Jesus by the will of God, To the saints who are in Ephesus, and are faithful in Christ Jesus:
Paul and Timothy, servants of Christ Jesus, To all the saints in Christ Jesus who are at Philippi, with the overseers and deacons:
To the saints and faithful brothers in Christ at Colossae: Grace to you and peace from God our Father.
Paul, Silvanus, and Timothy, To the church of the Thessalonians in God the Father and the Lord Jesus Christ: Grace to you and peace.
Paul, Silvanus, and Timothy, To the church of the Thessalonians in God our Father and the Lord Jesus Christ:
To Timothy, my true child in the faith: Grace, mercy, and peace from God the Father and Christ Jesus our Lord.
To Timothy, my beloved child: Grace, mercy, and peace from God the Father and Christ Jesus our Lord.
Paul, a servant of God and an apostle of Jesus Christ, for the sake of the faith of God's elect and their knowledge of the truth, which accords with godliness,
in hope of eternal life, which God, who never lies, promised before the ages began
and at the proper time manifested in his word through the preaching with which I have been entrusted by the command of God our Savior;
To Titus, my true child in a common faith: Grace and peace from God the Father and Christ Jesus our Savior.
Paul, a prisoner for Christ Jesus, and Timothy our brother, To Philemon our beloved fellow worker
and Apphia our sister and Archippus our fellow soldier, and the church in your house: