The rebounders I tested each have different G forces. Most people want higher G force at lower amplitudes so they don't have to jump so high to gain G force. When doing the Health Bounce, some springs are shorter and give more G force with shallower bounces while others give too deep of a bounce and decrease the G force. Buying just the right rebounder for a person's weight and health goals will help determine which rebounder to get. I have laid out nearly every variable on my rebounder quiz that can pinpoint the right rebounder.
Note: I urge people to get only get rebounders with high carbon steel otherwise changing springs every 2 years to keep up the tensile strength can be costly. High carbon springs lose minimal tensile strength and the springs have a negligible yield even with heavier people. If using the rebounder every day one might have to change out the springs every 6 months to a year. The springs are not likely to break but some people get frustrated when they try a new rebounder and it feels totally different than their 6 month old one. The Lymphaciser and the Cellerciser both have the highest carbon springs. The Cellerciser spring is 106 grams. There are other brands of springs that are almost the exact same size but weight nearly have the weight. The cheap springs that break all the time are usually the anodized aluminum springs that might have just enough carbon so that they don't break during their short warranty period. These are usually the 49 dollar rebounders at the sporting good stores.
Note: the springs with shorter coils will have a more sudden G force due to it not being able to stretch any further. This is the G force that I try to avoid. Tapers are what helps gives the pop at the bottom of the bounce after the belly of the spring or the spring just before the taper gives out. That is ok but not if there is no taper. The Needak spring is tapered and the Cellerciser spring has only uses the 2nd taper when needed while lightweight people will never usually use the 3rd taper (third tier). You only use the spring that you actually need on a triple tiered spring.