Byte balancing is super simple. I've provided an example in the Code Examples forum. So, it's not absolutely necessary that you change the hardware.

However, there may be other factors (e.g. cost) that would make a change more attractive but, without more detailed knowledge of the application, it's impossible to suggest other hardware. Is this a one time project or do you plan to manufacture a product? If it's a product, you'll need to meet FCC and/or CE requirements, depending on where you sell. What is the application? What range is needed between transmitter and receiver? Is a transceiver necessary or can you use separate transmitters and receivers? ASK modules are usually 20-30% as costly as FSK. There are some very good RF modules (made in China) available through an EBay store for extremely attractive prices (cheaper than dirt - even with collapsing real estate prices).