That's great that you have a good relationship with them, and I am all for trying…even when you know the answer is no.
You never know unless you ask.
That said, you are fortunate. I have never had this kind of relationship with any Sprint store I've ever been in. Since my first iPhone with Sprint (the 5) I have managed to avoid the Sprint store for the last three years. I've been in there maybe three times and none of those times were for iPhone issues.
Just had my 6+ replaced last Sunday. I went direct to Apple even though I have TEP. My deductible with TEP is $200 and all I had done was cracked my screen. $140 for a screen replacement in store, done by Apple with Apple OEM parts beats $200 to Asurion, a hassle sending the phone in, waiting for the new phone and hoping it's not typical Asurion refurb garbage with non-Apple OEM parts.
Because Apple had issues the day I went in, they replaced the entire phone for the charge of the screen repair. I have absolutely no idea what would have happened had I gone to the Sprint store instead.