Jest
I haven't said anything on how good these are and actually I have no clue.
However, as you ask, the last reports from Israel have stated the various Achzarit, Nemerah, and other Nakpadon (fairly similar) to be quite efficient in some type of combat, especially those involving light infantry. It seems that Israel doesn't see them as useless. It also seems that they met with some success during the last operations in Lebanon (2006), despite no victory for Israel. Of course, these reports being from Israel and the US army, they are highly unreliable.
By the way it seems that you are right, the idea behind them is to modify obsolete designs. Therefore, I find the vehicles to be interesting and they might be quite fun in T2K. I wouldn't be surprised to find similar conversions and such vehicles would pack some firepower with a pretty good protection. Not that bad on a theater where most surviving weapons will be assault rifle and heavy machinegun.
I don't thing they intend them to replace regular APC. They are intended to fill in a gap.