You'all do what you want. I break in on a stout Dino.
What's the rush to syn? The thing won't even loosen up until 40,000.
The first fill is based on the metallurgy. Mostly ring material, but also Ni content in the liners or the block, and the final hone pattern/finish.
Now I agree with getting the first oil out, and installing a magnetic drain plug, and slapping a plate magnet on the bottom of the pan. But, if it were my car/truck - it'd get syn-blend at best unless it came from the factory with synthetic, in which case I would know they had it factored in.
Maybe I'm old school (yeah I am ...), but reciprocating aircraft engines don't break in on synthetics, nor marine engines. Almost all the re-man shops and the OEM crate engines come with "use 10W-30 something" to break in. Or straight 30 HD, or something. I supose most OEM MFG's use a blend nowdays...
High end cars almost assuredly come with motors that have been dyno'd. That's a whole different beast than the Kia that was bolted in cold and expected to run first time off the line ...
Plasma faced rings and fine hone finish, yeah, I guess I'd use synthetic if I was pusged into it.
And when I say synthetic, I'm not talking HC Grp III. I mean Ester or PAO based oils ...
If you are going to put in HC Grp III, that's OK by me as it's just fancy Dino oil as far as I'm concerned