LTM,Websafe and APM upgrade from 11.6.1 to 12.1.2

When I upgraded my boxes from 11.6 to 12.1.2 I did not experience any issues with my APM configuration. That doesn't mean that there aren't any conflicts (I really don't know), but in my experience my upgrade went flawless. Just make sure you have a backup in case you need to roll back (System -> Archives -> Create)

Can't comment on the Websafe part of it.