Unfortunately, No. If you plot out the performance of the same drive with different cache values, it's not linear. But larger values do help, and it can be simplified to "get the largest available for the capacity".
Another way to look at it, is cache/GB. For example, WD's RE3 line. The 250 & 320GB variants have 16MB of cache, while the 1TB model has 32MB. And the smaller drives do run a little quicker. Other issues such as platter count are also factors, as the smaller drives are singles.
WD's datasheets show this in the specs, as does independent testing. Personally, I take what I can get.