it probably works like BootMii as in after it's installed [yes i know BootMii is software and wasabi is hardware but backup should follow the same principles] you can boot into the "backup" portion of the hardware or software and make a backup of your NAND then restore said NAND if any problems arise and you either semi-brick or completly brick your wii.
As far as using this to unbrick any Wii other than your own, i'm not quite sure. I've never used hardware for modding [free is for me ]
I'm pretty sure every NAND is specific to each console, so yes you may be able to get into recovery mode but without a backed up working NAND file then how would you be able to recover. [i'm not 100% sure on this so may-b someone could shed some more light on the situation]