I think that there's a psychological issue with paying more than my "usual-comfortable rate" which is this: if I pay the usual/comfortable/market-standard rate and the experience is mediocre, I chalk it up to experience. It's gonna happen from time to time. It's the name of the game. Win some, lose some (hopefully more of the former!)
But if I pay [what actually is, or what I perceive to be] a premium rate, and the experience is mediocre, it hurts a lot more, and I don't mean financially. It's the feeling (maybe only half-conscious) that there was an implicit bargain that, by paying more, the experience would be a premium experience. If the actual experience was poor, there is the painful feeling afterwards that the implicit bargain of premium fee for premium service was broken. And that feeling can't be just be shrugged off as part of the inevitable "win some, lose some" sequence, because a premium fee was paid!
I wouldn't myself be influenced by good reviews when deciding whether to hire a premium-fee provider. For me, two things are needed. First, a lengthy, thoughtful, profile, that gives a 'real feel' for their attitude and with some feel for what kinks the provider enjoys rather then simply 'provides'.
Secondly. a short phone conversation hoping to hear a relaxed, natural, confident-but-not-arrogant tone of voice, and a satisfactory response when I enquire about the provider's kink preferences (if there was any uncertainty after reading his profile).