Hi DC:
I have a 2016 MBP15 2.9 GHz, 16 GB, with the 460 video card to edit 4K/30FPS Phantom 4 Pro video. These are my observations:
- Premier Pro. Edits are tough because previews are "jerky" with no effects applied. If any effects are applied then editing is impossible. Almost always have to generate proxies to have any hope of editing. Rendering is also very slow with 2 minute videos taking 15 plus minutes
- FCPX. While not as advanced as Premier Pro, editing is far easier/faster. Previews of 4k footage without any effects has no or very little jerkiness. Almost no need to use proxies. Stabilization with FCPX is much faster. Rendering is very fast.
For the simple editing that I do, FCPX is the clear winner. I like it so much that I am considering dropping my Adobe subscription.
Now more to your question about drone footage, iMovie, and the two 2017 MBPs you are considering. My guess is get the one with the 640 video card.
I did a quick test for you using iMovie on a 100 sec 4K/30FPS video Phantom 4 Pro with my 2016 MBP15. Applied auto correction and stabilized. Rendering in iMovie took 2:40.
Do you have have some drone footage that you can take to a store that has these two models for you to test to decide which might be best for you?
More information in my reply than you requested. However, I hope that it helps with your decision.
Don