asterisk users - Feb 2008 - Considering replacing ATA with linecard.

One of my ATAs became unreliable recently, and I replaced it with 2 ATAs 
that I had spare (a PAP2, and a cisco 186).

A while back, I replaced an spa3k with a linecard (the spa3k now is only 
used to connect the FXO and FXS ports during a power cut).

I am considering replacing the ATAs with another linecard. (idea being 
that it will be a lot tidier, running less kit and would probably be a 
lot more efficient/reliable).

Is there any real advantage to doing this?
Does anyone know of a cheap off the shelf bit of kit I can use to 
replace the spa3k (since all it is doing now is connecting one par of 
cable to another in the case of a power cut).

TIA for any help with this.