From my analysis, there's around a 3.9% abnormal return associated with a L/S beta neutral low beta strategy (long low beta, short high beta). It's Sharpe ratio is ~1, though. 3.9% is pretty significant, especially since the beta correlation is less than 2%.

There's a reason why these factors are called "persistent." For systemic reasons, it is hard to arbitrage them away, mostly due to laws, and sometimes tax implications.