Yeah, I tried it out for a full day at work, and it was a lot more fatiguing than I expected. That might be because I'm more used to 30g and mx reds (my two switches of choice.) But I wouldn't call 45g too heavy, they just feel a bit stiff. Not being able to type without bottoming out is tiring. I have a feeling my fingers will probably adapt after a few days though. We'll see.