I must confess that I have not found much time yet to really get into tinkering with my own IIgs setup, but didn't one of the ways they attempted (for cost-cutting and corporate-image consistency purposes) to "converge" the Apple II vs. Macintosh departments within Apple involve unifying the peripheral lineups to some degree? I was under the impression that a IIgs had the same kind of serial ports as a contemporaneous Macintosh (namely RS-422/423, which can interoperate transparently with legacy RS-232 gear _regardless of whether as DTE or DCE_, by connecting only a specific subset of the pins in the cable in either case). While it has been years since I physically looked to see if that is in fact the case, the hypothesis is partly corroborated by the fact that a IIgs can do LocalTalk (not actually impossible with a traditional RS-232 port, at least if the right serial chip is controlling it, but not nearly as easy).