The MTS file is Sony’s AVCHD which is based on .H264. It’s not an editing format, it’s a delivery format.
The advantage of using 5DtoRGB is that it can “correct” the footage from 109IRE to 100IRE. You have to do that manually in FCPX. You can also use CLIPWrap to reconform slowmo footage.
but here i suggest you to change the avchd to prores 422, 422hq or prores 4444 for final cut pro by using a third-party tool , which will make the steps easier. Did you agree with me ?
https://format-shifting.tumblr.com