I was told by Losi drivers to use the complete 1.0 servo saver assembly, not just the spring. It looks to me like the 2.0 are more angled and would be more difficult to engage.
With the 1.0 T, some people were complaining because it was "too soft".
I'm running 1.0 assembly with the 1.0 Fioroni spring and no issues at all.
the Original 1.0 saver setup was Rock Hard it would barely engage due to the Flat edges the saver plastics had....Now that they are curved the right way it works like it should....the spring is all that's needed.