Are MIPS helmets actually any safer than standard helmets? Independent Research?
Summary

Research into brain injuries has been ongoing, but tended to focus more on direct impacts. In the last 70 years there has been more research into rotational brain injuries, and in the 1990s and 2000s scientific, evidence based proposals were made to reduce these. The Multi-Directional Impact ­Protection System is an implementation of these, and it's effectiveness has been validated by independent research. 

Discussion

There is lots of research into brain injury. While much of it has focused on direct impact leading to scull fracture, the effects of sudden head rotation have been studied since the 1940s. These (pay-walled papers) are typical


A study on rotational brain injury (1984).
Physical model simulations of brain injury in the primate (1990).


Such studies progressed to proposals, such as


A proposed tolerance criterion for diffuse axonal injury in man (1992).
KINEMATIC ROTATIONAL BRAIN INJURY CRITERION (BRIC) (2011).



  [In] 2008 ... Swedish neurosurgeon Hans Von Holst, along with mechanical engineer Peter Halldin, developed a new technology called MIPS (Multi-Directional Impact ­Protection System). 


A couple of (non independent) articles are 


New Helmet Technology Reduces Brain Injury 
MIPS


Mips has been received with acclaim


Precious Protection (2010).
Senseless: An In-Depth Look at the State of Bicycling Helmet Technology (2014).


There has been at least one study of their effectiveness 


Angular Impact Mitigation system for bicycle helmets to reduce head acceleration and risk of traumatic brain injury. (2013).
This found a 34% reduction in peak angular acceleration and predicts that AIM helmets reduced the risk of concussion [by] 44%.


But not everyone is convinced regarding helmet effectiveness. For a helmet skeptic's view see


Cycle helmets and rotational injuries.
The views expressed here are out of date, but it's the only skeptical view I found regarding rotational brain injuries.


Certainly, more independent validation would be good, and in future better designs could appear. At present MIPS seems to set the brain protection benchmark.