There do appear to be vendors advertising a 4.8+6+6, but with that noted, a nominal value of 4.5uf is almost within the low end tolerance range (often 5%) of the (nominal) 4.8uf capacitor. The fan speed would be lower at settings utilizing the 4.5uf instead of the 4.8uf, but I couldn't say if that would really be by a noticeable amount or not. Some settings will likely use the 4.5uf in parallel with one or more of the 6uf's, and for those settings the influence of the difference between 4.5 and 4.8 would be proportionally less. Too low a capacitance value can create a problem with fan startup, but I'm suspecting that wouldn't be the case here since fan startup is usually at the highest speed setting and that would likely use capacitors in parallel.
