If swapping out Gen 4 links with Gen 5 OEM links, do you need to also swap out the dogbone from Gen 4 to Gen 5?
Yes. Gen5 link plates require Gen5 dogbone (longer).
This for either keeping Gen 4 shock or moving to either OEM Gen 5 Shock or Gen 5 aftermarket shock?
Confusing but interesting to know for future upgrade purpose.
Using Gen5 link with Gen4 shock makes system harder, now you have like 120 spring istead of 110, more compression and rebound damping. This could be bandaid fix for weak Gen4 stock shock rebound, but requires lighter spring for light rider.
Using Gen5 link and Gen5 shock you should get roughly same rear end as Gen5, minor bit harder, since swingarm is shorter.
Using Gen5 aftermarket shock you use Gen5 link too, with gen4 link system will be too soft.
Using Gen4 aftermarket shock you must find out if it is valved for gen4 stock shock or already revalved for aftermarket link (MSS, Kyle, Attack), in this case you use gen5 link because it is very similar to MSS links.
I use Gen4 aftermarket shock (what is revalved for aftermarket link) and Gen5 link. Never tried stock shock in any configuration.