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.