Not really. The JD MK4 needs a long time to charge and you don't necessarily see it charging when the charge started outside sensor range. That can be seen in the video I posted in the Erzieeffinghero thread. The problem is not related to cloaks, it is only related to cloaks combined with JD MK4, and JD MK4 used on the Geb, which is a baecruiser.
Please don't turn this into another cloaks-are-bad instrument, because the only bad thing about cloaks is the potential to buttcloak people. I rather have 50 people flying around cloaked than 50 people not being logged in, since cloaked people can be cloak-disrupted.