@ALEX00 is right. you really wont see huge speed increases due to the fact that hard drive spindle speed plays a part in the reading/writing of the data as you download.
if you really want to get an edge, look at a dedicated server with an ssd drives, might be more money but it will be very fast.
u can try souyoustart.co.uk for example.
Their game servers are SSD options, the pipe is 1gbit down but only 250mbit up. and the server if you are lucky enough to grab is good for only 2 weeks. But that should give u an idea if thats what you want.