I have a hydraulic flat tappet cam in my 354 Hemi and have no intent on changing anything. Thousands of stock cars and drag cars, as well as street modified cars, are running engines with flat tappets with zero problems.
The key is BREAK-In oils... after the cam has broken in, and the engine run for sometime with a high zinc oil, you can get away with an oil with 1000 PPM of zddp... Once that zddp become a phosphorus coating on the cam, bearings, etc. it will stay there as long as you avoid the SM oils (which have high calcium which east away the phosphorus coating).
The new SM oils have a minimum of 400 ppm... not enough... but they have a maximum of 600 ppm... still not enough. But the feds only require low zinc levels in 10W30 oil and thinner... look at the API label on any 10W40...it will not be an SM oil. Likely an SJ oil...higher zinc levels.
Spending extra $$$ on a roller simply to try to avoid a potential (and avoidable) problem is wasting money...IMHO of course.