I have a reasonable collection of J (QF) kits in my bathroom cupboard! I have J kits starting from the best ever Green Canvas type from approx 200/2001, the blue ones, the plastic ones and the zip up MN type - my fav. I have a couple of SIA J kits as well - basically socks, eye shades and a bag.
I keep my optical drive and a 12V/230V inverter in one and is left in my luggage (the inverter is sometimes removed in advance for a flight but less and less now), and I frequently keep one in my small Mont Blanc lappy bag (space is a premium) which stows myriad cords, a digital camera and spare SD cards, a laser mouse, a couple of pens and spare business cards without distorting the shape of my bag (which is important - ask QF009 if further explanation is required!).
I keep them all if space allows, and have given quite a number away in the past to basically whoever wants them.
Mr!