I use the X-T3 now for 14 months. Highly recommended. I also have Tentacle Sync E and edit in FCPX. Syncing using audio works well in FCPX or Plural Eyes for short clips, such when making movie and clips are not likely to be over a couple of minutes. If you are shooting an event, like a concert or theatre or conference then syncing via sound is almost impossible (with any camera), because of ambient noise and because the program would have to find every clip's audio in a very long separate audio recording. In such scenarios, I recommend not to switch off the recordings (might need an external recorder if over 30 mins), OR use an audio TC generator.
I favour the Tentacle Sync (E) system for the following reasons:
Probably the lowest cost, especially when you factor in the included license for Tentacle Sync Studio program
Very easy to use
Has on-board mic for recording scratch sound on the Right channel (Left is used for audio TC)
Now if you have unrestricted budget, need longer range than Bluetooth and have extra devices to sync with, such as electronic slate, then you might want to look at more expensive alternatives, otherwise it is hard to beat what Tentacle has to offer.
Back to the X-T3. I use Auto Level for external mic input and plug in the Tentacle Sync E. I record audio with a Sound Devices MixPre Mk 2 recorder (good alternative is Zoom F6). I use my iPhone as time master for TC, as that is tracking the mobile network atomic clock link (however real time accuracy is not important as long as everything is synced to each other). I then jam sync the audio recorder from the Tentacle, which can then be disconnected and moved to the camera. Additional synced Tentacles are plugged in to additional cameras.
Only preparation, which will be required with any camera, is to do a test recording with a slate clap, and determine the video delay, between audio and video. This is due to the camera's video processing. I find that the X-T3 is 4 frames at 25 fps or 160 msec., but check your own gear. You then apply this as offset in the Tentacle Sync Studio, which will convert the audio TC to file TC that your NLE recognises. All this is well documented on YouTube.
Hope this helps...