Nice remix man!
Changing the lead to the piano was a nice touch, the intro had a really nice sound to it. The vocals sound a bit out of beat in some places, (0:19, just the first few words)(2:08), but its nothing really major. The synths and vocals were mixed well together, and everything seemed to have its own spot in the track.
As for the mastering, I think your putting to much thought into it in my opinion. The limiter is pushed way to far in this and it is very noticeable. The drop should sound louder than the build up, but it actually sounds quieter because of all the compression. My advice would be to simply not push the limiter as hard, and focus more on mixing the levels properly before the master limiter. This will give the track a greater dynamic range, and the drop will instantly sound bigger. In short, focus more on mixing, less on pushing the limiter.
Musically though, I really liked this remix. The mastering will get better as you finish more tracks.
Keep it up
OAKUM