Your using much better tools than I have Geo74. I just checked your examples and the quality of your picture at the edges is much better than mine.
2.7K is lovely to work with and I have tried that, the only downside is the video files are that much larger.
I sometimes use the fisheye reduction tool made by Crumplepop for FCPX.
Warp stabiliser has been proved to be a far more successful stabiliser than anything else on the market. I don't have access to Adobe Premiere Pro CC at the moment. I can afford to buy it but I don't know if I can bring myself to buy it (or rent it) just to get access to the warp stabiliser and the lens distortion cure. I wish those components were available as a standalone.
I really like using FCPX so it would be hard to switch, but then again we are all striving for that perfect picture quality.
I have seen your films before. Its good work.
Are you using a Mac?