When I'm at my desk my Evods, PTv1, RDAs, etc are all vertical on top of my Egos/mods. At night, I tend to lay my main device down on its side on my nightstand to prevent me knocking it over when I invariably toss and turn, get out of bed, or reach over to smack the snooze button on my alarm. I've seen no real difference in either method unless the tank-type setups are very very low on juice, in which case I can be greeted with a dry hit from having it on its side all night if I don't flip it vertical and let it wick up again. Now, on top coil devices, I would recommend leaving them laying down if not tilted back towards the mouthpiece if possible, as it keeps the wicks wet, but it's the opposite on bottom-coils like the gear you're describing..those are going to be happier standing or on their side with the liquid pooled at the battery end.