I wonder how long it will be before the first one is shot down and lost ...
It's never about being shot down or not, it's about transforming Ukrainian equipment to western standard. So the support that come later is going to be a lot easier.
You can shoot down an F-16 if you want, the issue is not whether or not the individual lost that is the problem the issue here is if you shoot down a Mig-29 or Su-27, you can't supply another airframe, and all the rigging done to those airframe so they can carry/fire western weapon is gone, which mean you need to do that on another Ukrainian airframe.
With US/Allied supplying F-16, you don't do need to do anything to fit western weapon on them as it was already configured with western weapon in mind, that save both time and resource and you can put more effort into the aid itself instead of spending them jury rigging the Ukrainian airframe. You save 5-10% of those aid money just because you don't need to do that anymore.
On the other hand, airframe loss isn't really an issue, as long as the pilot is saved, pilot don't generally go down with the aircraft nowadays, you shot down a F-16, US have 450 stored in Neveda and they are ready to go. Ukrainian pilot would just hop on another aircraft if they were shot down, as they aren't chasing Russian fighter in Russia, most of them will be landed back in Ukraine if they were shot down.
