I had the same problem when i started vaping. I think this might be a common thing with vaping. When i first got my PV, it was harsh on my throat, but tat went away pretty quickly. But for, maybe two weeks, vaping was really hard on my throat in the morning. Kind of felt like when i first vaped/smoked a analog when i had a cold/sore throat. But, it's fine now... Either way, i don't think it had anything to do with the equipment, of course, a different/lighter juice could make it easier.
Hopefully more people chime in, I've wondered if this is something every vaper goes through.