Hey, nice song!
I think the switch to an acoustic song turned out really well.(Although I'm personally not an R&B fan so you could have changed it into a country song and i would have liked it better than the original)
BUT....
I think it would benifit with a fuller sound later on in the track. Maybe some sort of percussion?... (I've always wanted to put a djembe, or cajon in a track xD)
I feel you create a good build up the choruses when you throw in the crash swells but when the actual chorus kicks in there just feels like somethings missing..