Sort of off topic but wondering. When you wipe everything what happens? I just installed twrp 2.3.2.3 and its a little scary taking that step.
someone correct me if I'm wrong, but think of wiping cache/dalvik like clearing your cookies in your internet browser - it won't erase data, it just clears out any hanging processes
wiping system, I think, deletes any ROMs/programs
factory reset wipes data/etc....
I always do that when flashing a different build ROM.
when upgrading a specific ROM build, you can just wipe cache/dalvik and you'll retain your apps/data/etc. the new ROM just writes over/replaces any duplicated apps