IMHO, anything capable of lifting will be used to lift more than it was designed for. I would think long and hard about going with lesser steel. However, with that being said, you are making a big jump going from 1/4" material to 14 gauge. I woiuld think you ought to look at MAYBE 3/16" material or 11 gauge. When in doubt, we always use heavier steel and with the exception of items we have to lift in the air routinely (like metal platforms on the top of a 70 foot scissor lift sitting on a pad on the side of a mountain - which we do from time to time) we have been pleased we did. We have many jack stands we built in 1968 that we have used in so many ways over the years and they were great investments in time and material.