Hyrules: The rule of thumb is if your
house is less than 3000 sq ft, a Passive
Coupler is adequate otherwise a Coupler-
Repeater is better. If you do decide to go
with a Coupler-Repeater, get the ACT
CR230. It costs more, but others have
reported problems with the SmartHome and
Leviton brands of Coupler-Repeaters.
With regards to Passive Couplers, the
hardwired ones are slightly better than the
plug-in ones since you can put them closer
to the electrical panel to keep the signal
as strong as possible. One other word of
caution is 240V modules will NOT work if
you have a plug-in (both 3 and 4 pin) or a
2-wire hardwired phase coupler. If you use
(or plan on using) 240V modules, get either
a 4-wire passive coupler or a Coupler-
Repeater.
BTW: A good source for 3rd party HA
products is AutomatedOutlet
(
http://www.automatedoutlet.com/).
I hope this helps.