is it safe to swap ps3 internal harddrives? please comment

i had wd 320gb inside my ps3 which is working perfectly, i got another segate laptop harddisk.

I want to test seagate harddisk in my ps3 without backing up my wd 320gb.

is it safe to swap segate test it and then swap back wd 320 gb without formatting it.?

i know segate would be formatted to ps3 format thats ok but just want to know when ill plug back wd 320gb will it be formatted also?

Please comment i got tons of stuff in my ps3 which i dont want to lose for now.