Unraid 100% doesn't care about the order / slots.
I had some USB-HDD adapters of various brands. If it wasn't going to survive a move and re-arrange, it already would not have worked. In my case, some of the USB-HDD adapters passed through the drive serial numbers and some did not. For the ones that did not, I couldn't have more than one (because it couldn't tell them apart).
ZFS AnyRaid soon?