Update!
I ended up buying this Voyager-sized Jetfire (
https://www.tfsafari.com/products/incoming-4th-party-tnt-01-tnt01-ko-if-ex30-cyguns-skyfire-jetfire-oversized-version-18cm?_pos=4&_sid=d8cc24c9d&_ss=r), just because he stands eye to eye with Siege Starscream, and I have to say, it's amazing. Not a replacement for Siege Jetfire, of course, but a great addition to the Jetfire shelf.
I got Sky Lynx instead as my choice of Commanders, and I have to say, he is incredibly basic, but in the best possible way. The transformation isn't needlessly finicky; all modes are straightforward, and he's actually enjoyable to transform. Looks like he stepped straight off the screen; plus the base mode actually looks good, rather than the robot mode doing splits afterthought that is sadly endemic, especially in Titan class.
The only nitpick I have is that the wings don't really lock into place all too well in shuttle mode (unless it's just me).
Well done, John Hasbro. Well done.