I've been going back and forth between the Mac Pro and 15 inch rMBP. Mac Pro is overkill but I'm worried that I'll be using it in desktop mode mostly. The reason I'm choosing between the two is because of the 4k monitor I have. Otherwise I'd select the 27 inch iMac. Is there anything wrong with using the rMBP in desktop mode maybe like 60% of the time? Would that hurt the battery if it's plugged in all the time?