The standard commercially available LS3/5a's didn't come with thin wall ply construction. It was considered too expensive.

Having heard BBC 001 & 002, which are not thin wall vs some thin wall, I would say the matching of the drivers and crossovers has more effect than the cabinet. Or maybe they just need 30 years of running in

Some manufacturers made signature or reference versions with thin wall (Kef and Harbeth for instance). It is possible to buy reference cabinets from Stirling Broadcast who can also supply all the parts.

The clones were made using a pair of Chartwell LS3/5a's as reference and with the help of a couple of members of the mailing list for listening sessions. They knew they could compete so made them off spec, but kept to the same size.

 

Coming from you James that is almost a compliment