I priced the 300 this morning $4400. $2200 when I bought the Panasonic late last year!Really a crap situation. Sorry to hear about this.
I've actually found that sometimes with the 5.2 I'll turn on the camera but the lens isn't latched all the way. This was due to the way I hold the body and hit the lens release button. Thankfully I haven't experienced this with the 1.2, yet. Although I do echo that I think the 1.2 buttons are much more squishy than the 5.2 buttons; I do miss the tactile response of the 5.2.
Is 300mm to 400mm really that big of a difference? It's too bad that I see that you don't want the 300/4 + tc1.4. I think that would be the logical step for you. Better reach and (expectedly) better iq at 300mm AND 400mm.
End of financial year sales imminent. Not sure what that means.
AC12 I'd thought same as you re a cover.
But I've also devised (in mind) a strap linking the two mounting screws for tripod base plate. Doesn't worry me they're another thing to undo if I need to change the lens. That doesn't happen unless I drop the lot