Lifter Technology Selection

Beyond the issues with the execution of the selected lifter system in an old Mopar block, how do you make the call for the more expensive, harder to execute roller hardware? It usually comes down to cost in a street or street/strip build.
I get the difference between solid and hydraulic tappets and understand (I think) why solid work better at high rpm. It's more a combination of valve action at just off-the-seat lift ranges, and valvetrain stability at high rpm.
So awhy would you go with a roller over a flat tappet?
In all but all out efforts - I wouldn't. Because of cost to properly prep a block for a solid roller, and the cost of the cam. lifters, and oil pump drive (in most cases).
Reduced friction so more HP?
Friction reduction is less about power and more about NVH and smoothness in the milder combos. Flat tappets are not high friction - if they are working right, the lifter face turns as the lifter moves it, and the lifter is mostly suspended by an oil wedge in it's bore.
Do hydraulic roller do better at higher rpm than hydraulic flat tappet?
Depends on the lifter design, bore clearance, and the lobe design. But mostly the roller does not rpm as well because it's a lot heavier and more valve spring pressure to control it. Spring pressure is a problem for hydraulics of any type.
Seems solid roller would be the ultimate but it doesn't seem like many folks use them on street engines, or at least to the extent that solid flat tappets are used.
Many use them. Many are trying to cheap out on getting them in the engine and don't make the power they should. And don't check springs or rebuild lifters as they should. Or run camshafts not designed for street type driving and use.