If you look at a typical mining pool for cryptocurrencies, you will notice that most of them contain a "Hall of Fame" segment. Upon closer inspection, you may notice that some people clock in at some absurd number like 140954085 mhash/second and get x number of some cryptocoin (let's say it's 100 BTC). One row down, you may see some user who clocks in at 43948 mhash/second is getting 10 or 20 more BTC than the user getting x number of BTC. Statistically, this means that there is little to no correlation.
The race for building the "best miners" seems to have been a rat race instead of one to the finish line. Save your cash and read the documentation. The transmission protocols used in cryptocurrencies are based on the same ones used for your favourite BitTorrent client and relies on open connectivity to the network. Hash computations aren't going to solve any quicker when the original algorithm by Satoshi was meant to actually be a self-evolving blockchain.