Oh, i was not aware you would be interested in my noobish first attempts fail-log. i made a log but discarded when 2nd attempt worked...
yes, i had cm11 and saimaa running without sfdroid and multiboot and did not wipe, only "full flash" procedure as discribed.
Going to replicated it, my nexus5 is for pure fun and testing anyway until gps works, chr chr.

Maybe the discription could be updated with where to best store the flash files so they persist wiping the data?
I ended up placing them in /firmware without mounting it.
Worked after some needed trial and error because i had no USB-OTG adapter.