I only have 3 MISB Transformers. A Car Robots Black Convoy, a Encore Convoy and a TFC 06 Megatron. I dont have a good reason they have never been opened, guess I just never felt like opening them. Everything else I have is either MIB or Loose and I have no regrets, its always fun to play with them.

Also if a toy has a battery in it always open the box to remove the battery, it's better to have it MIB and working than MISB with ruined electronics.