If you could get some information on the degree of testing and refurbishing that they have had and the length of the warranty then you could consider them.
Especially important is if the packs have been rebuilt with new cells and if not the degree of testing they have had which would make the warranty even more important.
NiMH batteries for instance have an average life of 4-600 charge/discharge cycles, possibly up to 1000 cycles if they have never been subjected to temp. extremes, overcharging ect.
If they are only tested and not rebuilt then I would pass...without actually disassembling them it's nearly impossible to judge remaing life except by examining the degree of anode and separator degradation for instance.
These would be considered end of life at 75-80% of capacity.