Have never found a practical use for a spring version of any rack - maybe I missed out somewhere. I do have the non-spring version of that same rack.
The big question is - is it the rack or your current pannier bag profile thats the problem? Generally panniers tend to have similar heights, but differ in lengths. So the larger ones, unless they have diagonal cutouts, cause healstrike issues on anything short of a full touring frame as they sit further forward AND further backwards. So before you drop your money - how have you decided that these will be any different than what you have now?