The 673 Guide Gun should be a little better handling the Magnum calibers than the 600 and 660 did. The 673 has a longer barrel than both of those older models.
I believe the 6.5mm mag and the .350 mag will again be the ones to have in time to come, for collectability sake, but who knows for sure.
I toyed with the idea of buying a 673 not long ago. I could never make up my mind on which caliber to buy, even tho the 6.5mm mag is the one I wanted. So I didn't buy any of them............yet.
Then, wouldn't ya know it, Remington offered a 35 Rem in a 7600 Carbine. So the 673 is now in the back seat.
So many guns.............So little time.........