The 505 design starts to show its age.
I see more the reviews here and on the gravel forum, as a result of Carbonda's frame quality and service, than just this specific model.
If I remember well the 505 was the first of their frame to be presented here.
We should ask Wing about the availability of the 606.
maybe you think about the 505 because it's your mate for a long time now. Regarding the style and maximum tire width it's in any case more road bike related than other frames.. but the optic with the low seat stay is not old-fashioned
From my side the newer gravel frames got longer and longer which is somehow weird if I want a more relaxed body position as in a pure road bike.
Taking a shorter stem by not changing fork steering angle and offset to much creates a uncomfortable riding (at least to me)
My 505 is roughly 2 years old now and I think the frame shape is pretty up-to-date. And I am fine with 40mm maximum
. For more I'll take my 909