The major issues you have with a dead PRAM is battery swapping. If you pull the charged main battery out for any reason it will not turn on again from battery power, you have to plug it into the wall and then it will run from the battery pack. I don't use my Wallstreets away from the house much so that is not a big problem to me.

The PRAM is charged while the system is plugged in (takes a day or so to fully charge a new one), so any coin cells you use need to have a diode to keep them from getting charged or they will tend to blow up. If you look on ebay long enough you will find cheap new PRAM batteries, the only issue is ripping apart the machine to install one.