A proper merged collector will add performance , but they are not a one size fits all kind of deal.
Thinking you will get a huge difference will leave you baffled and / or disappointed unless you take all the variables into consideration when building them.
And even then , the difference won't be felt in the seat of the pants.
I could see them in a heads up , every ounce of oomph kind of deal.
Otherwise , it's more for show and tell.