IMHO - THE S-38II is a newer version of the S-38. I talked to JBL customer service and they said the differences are all cosmetic rather than electronic. Basically needed to drum up sales on the Studio Series line so they made a few colour changes and called it the latest greatest.
The S-38BCH you are referring to is probably the beech (or is it beach) coloured version of the original S-38.
IMHO: I heard both S38 and S38II (costing here the same), and I preferred the S38II because: a) The sound was cleaner and louder (a litle bit), b) They looked nicer, c) They're more stable [yes, the S38 base is very unstable].
I can recommend the S38II over the 26s due the bigger size and better [for me] sound. The 26s are a option if you doesn't have enough space (perhaps to put them on a shelf).
Maybe he's thinking of the N38's. They are very forward heavy and promote tipping. I think the S38's are as solid as you get. You'd need a baseball bat to shake that from it's shelf.