[Asterisk-Users] Wildcard X100P or TDM400P?

[Spencer Nassar]

I'm looking to add a single FXO port to my Asterisk box.  It looks like 
my options are a Digium Wildcard X100P off eBay for $6.99, or a 
Wildcard TDM400P with an FXO Module from Digium for $125.

Can anyone explain the tradeoffs (other than the ability to put 4 
FXO/FSO modules on the TDM400P).  What about RTC for the system - I 
know the TDM400P provides it.  Does the X100P?

Thanks!