I have the Systainer cart part #492388. And right now all I have is 3 systainers and 1 sortainer on it. I know right now its not a problem but when should I think about getting another cart? I am not interested in building a shelving unit to hold systainers because we are going to be moving in the next year and I dont want to put the time or money to build it. Plus I like the mobility of the cart. I dont want to invest in the Systainer Port.