Personally, I have a major dislike for daisy-chained control buses like
this.
All it needs is one box at the start of the bus to go bad and you've lost
control all the other boxes on the bus.
The same thing can happen with Ethernet or
any communications protocol that uses a
shared wire/medium. However, given the fact
that RS-232 is an extremely well understood
and simple technology, I don't think there
is much risk in using an RS-232 daisy-chained
control bus.
Of course the embedded systems folks
might be able to make a case for I2C or
HP1B or something else that is used in
industrial and laboratory control applications.
--Michael Dillon