My son
Firstly, you have anticipated wisely, my concern about possible spongyness.
Well done, and yes, if you feel no spongyness, the soles are fine.
Worry yourself not over the worn welting trench revealing the stitching, for this stitching is (arguably) as tough as the leather soles and will wear well for many many wearings to come.
You could have the rubber (or vynil) sole guards applied for under $25. Yes, this is going to thwart off the inevitable sole replacement, but it will also give a thicker and heavier feel to the shoes. Now this doesn't bother me in the slightest, as I have had this done to several pair of my own AE's.
The purists will poo-poo the sole guards but I see it as a practical solution.
Afficianados will argue that the sole (and your foot within the shoes) will not breathe properly with sole guards, and also that they are just plain tacky.
My argument to this, is that there is plenty of exposed leather left on a shoe to properly breathe and so sole guarding is acceptable.
If your intended use for the shoes includes enjoying a brandy cross-legged in a wing chair at the boys club, then do not sole guard. If you intend on keeping your feet primarily on the floor or sidewalk, then sole guards will not ruin the aesthetics of the shoes.
The only time I would be opposed to sole guarding, is on double-layered soled shoes (example-Florsheim Kenmoor, AE MacNeil, etc) because a double-layered sole is already quite meaty and sole guards on top will make them look and feel like FrankenShoes.
