NorCalFJ100
SILVER Star
I suppose it certainly doesn't hurt to have the pump. But I've never had an issue without it. I use mine pretty regularly. Cold weather has been the only issue, but that only affects the foam not expanding properly.I used a cheap little 12V one from Walmart and as someone who inflated and deflated it every night for the better part of the year, it was definitely worth it; although I admit the little air pump is a little bulky and i don't plan on keeping it long term. Eventually i'm going to do what everyone else does and use the on-board air to pump the bed (just gotta figure out a mounting solution for the compressor @grinchy donated!).
It all depends on how often you plan on using it, versus how much the real estate/storage space in your car is worth to you.