Remember that each Invincible part costs 6 airframe capacity, and you only have (ship rank)+11 capacity to work with. Bronco parts use 3 airframe capacity, so an all Bronco rank 1 ship is at 12 out of 12 capacity. You can't use Invincible parts at all until your ship is rank 5, even though you have enough capacity at rank 4. If your ship is rank 13, you can have an all-Invincible ship.
Invincible parts are nice, and you can't use Enterprise parts until rank 15. They're a good upgrade from 5-15, and even then, at 15, the best you can do is Bronco, Invincblex2, Enterprise. You won't be able to run a second Enterprise part until 17, and that's with dropping down to double Bronco for the other two bits. So, yeah - Invincible isn't a bad choice. I find it helpful to have at least one of each part so you can fine tune your ship later.
Spreadsheet update: To speed up access, reduce load, and provide a place people can enter logs when the main sheet is down, I've split the sheet into three sheets. The main one will not have any analysis running on it, and it will not have features in transitory stages anymore. There are two new sheets:
FFXIV Airship Logs - Quick Reference
The Quick Reference sheet is supposed to be easy to read and easy to use. It does not have a copy of the voyage logs and contains no dynamic data. It has a static version of the sector list which incorporates extrapolated data and data reported elsewhere to make a solid table of item drops. The distances were moved to the end for that sheet. It has the ship builder and trip planner. At the end is a backup public logs tab for when the main sheet is down. I will not be checking this tab nearly as often as the other, but I will still check it and update the master list from it.
FFXIV Airship Logs - Analysis
This sheet will be used by myself, Bonzai, and anyone else who wants to do calculations on the data. When someone wants to do a fresh calc, we'll update the sheet with a current copy of the master voyage log. Honestly, this sheet isn't terribly interesting unless you're doing calculations with it as we'll report any findings here. If you want edit access, please ask in a way that tells me your google account name and I'll give it to you.