To start with, there is a much larger difference between horns than between boxes. Stats are actually extremely similar except for some differences which are minor in nature. There is no similarity to the sound between Cessaro, Tune Audio Anima, Trios, etc. A guy who likes Cessaro could like the Logans and not the Anima. The variations in bass, tone, everything, are massive.
Now to vintage horns, which are again different sounding from some other horns. I have heard only two - WE and Bionor. I am not a fan of the K2 or Pro JBL series, haven't heard the vintage. I loved a DIY JBL horn though.
It will be impossible for a stat or analysis to touch the midrange magic of a vintage horn done right. To start with, the valves used, whether David's Lamms or the WE 300bs (at Munich, you might get to hear the WE 300As, each valve costing 15K USD) itself will do more magic than any amp that can drive a panel. Not to mention the speaker midrange itself. Also, these speakers are made for TT playback. Somehow both on Bionors and WE, I did not like digital playback, and even one a 2k DIY TT, the WE made me melt.
I have heard WE both with Line Magnetic and GIP drivers, and you need GIP to get the magic.
I have not heard other vintage horns made from Altec so can't say about those, but they will sound very different. There is a lot of DIY with Altecs too so there will be many differences.
There is the driver, the shape of the horn used, and the crossovers and material. The WE for example are usually made of wood except for the 16A which is made from metal. I love their metal zing on strings.