any big advantage to using adjustable rocker arms

Main performance advantage comes from a weight reduction in the drivers wallet.

Sure you need adjustability with a mechanical cam, and it is nice to be able to fudge really bad geometry a little, but roller rockers are pretty low on the bang for the buck scale. Most rollers are heavier than the stock stamped rockers and even worse move their mass out over the valve tip, exactly where you don't want it. Theoretically you get better guide life, and if rockers were cheaper than guides, such would be a good argument.

Its your nickel.

Myself, I would buy titanium retainers so I could run a lighter valve spring, rather than adding weight to the valve train. Remember, the horsepower required to operate that valve train increases at the square of RPM.