I personally think that a blocksize limit is not needed. Simple soft limit set in client config file will be enough. (like 250kB/500kB/750kB soft limits before). You can see from blocksize history that most people just use the default value and the transaction rate increases whenever a new client that ups the default value is released.
Don't forget about the butterfly effect.
The configuration that has proven itself to work is the one where the soft limits (you mentioned) were timely adjusted, while the whole system was protected by a static hard limit. Introducing a minor change to the configuration (hard limit removal) may have a tremendous effect on the outcome. Incentives is the key word here.