Exploriments vs. Gizmos for pre/post/formative assessment and simulations

In looking for a less-expensive product for science simulations and formative assessment, I checked out Exploiments. From what I can tell, it's nowhere near the development of Explore Learning's Gizmos. But I'll have to have the science teachers try it out. they may like the higher-level math, but may not like the look and feel of it. It also doesn't seem to have the highly-developed pre and post materials that each Gizmo contains, with instant feedback to the teacher for accountability and monitoring.