Having something clocked higher but still cooler and quieter means either a bogus claim or a significantly better cooling system. These things can be measured, so you should look for such a review.
On the other hand, clock speeds are somewhat arbitrary. Not every chip is created equal, some run stable at higher clock speeds, some don’t. Most have defects to some degree. The best “eggs” are selected for premium products, the defective ones turn into budget hardware (That is, often they’re essentially the same chip but with the defective parts disabled). If ASUS believes they can sell you a slightly overclocked chip while keeping RMAs at bay, it’s not necessarily a problem.
Either way, a 10% or similar increase in performance is something that is practically unnoticable in practice, so I wouldn’t pay a premium for it. A better (quieter) cooling system does however pay off, in my opinion.