In my experience, yes. 49 MHz Bits and MicroSizers have a greater range than their 27 MHz counterparts.
However, in my experience the 57 MHz Fairlady set has great range as well. I have heard from many others that they do not get good range at all with 57 MHz.
I think a lot depends on interference. All I can say for sure is in my case, 49 MHz yields a much greater range than 27 MHz.
its easier for a higher frequency to travel through the air hence 57 will be stronger than 27 at a given distance if both have the same power driven to them.