Sure, subtyping adds additional pain points (mostly separate from overloading, BTW). But I think this is mostly orthogonal to reified vs. erased generics. As it is, the .NET runtime supports reified generics and declaration-site variance (albeit limited to interfaces and delegates), and to my knowledge there's nothing stopping a different language/runtime from implementing reified generics even with usage-site variance (and Scala's type system only has declaration-site variance, anyway, AFAIK).