The first thing to do is find someone else that has the upgraded package on the same internet provider. Get them to use a bandwidth tool to see what they are actually getting as "up to...." is always the terms and conditions.. so if you find they regularly do not get "up to" then don't bother.
Don't forget it is always the slowest link in the chain anyway, so although you may get a lot up to the ISP's router, where they link in makes all the difference.