I have been using them for several years on my Sports 2000. They really help reduce friction in the suspension -- you may find the shocks needs to be valved 20%stiffer to compensate for the friction that the springs impart upon the shaft seals. I think they really help cars in low-grip situations (like rain).
That said, I'm not sure they would benefit an IT car unless you've already reduced the suspension friction in obvious ways (no rubber/plastic pushings, only spherical bearings or roller bearings, high-quality shocks/struts.