Not sure if its the same Softraid they are talking about (
https://eshop.macsales.com/item/SoftRAID/SOFTRAID5RTL/ ):
SoftRAID offers 5 RAID levels: RAID 0, 1, 4, 5 and 1+0.
So it depends which level do they have.. I've a RAID1 on my system which is basically mirroring, so in your case that would mean 120gb.
Also maybe under SoftRaid they are talking about 'software raid' so RAID is handled by software not by a designated hardware.. but I don't think that's the case here.