Big block camshaft question

The HEMI cams have a different valve arrangement which means that the lobes on the cam are in a different order.
I made the switch to a solid flat tappet cam last year. I have not had to readjust the lash at all. Maybe it might need adjustment after several thousand more miles, but I have about 3000 miles on this setup.
I have considered going with a roller cam a few times but I've never been able to justify the expense considering how little I drive the car. I've heard that the hydraulic roller lifters do not last long if the engine spends a lot of time idling. I am not sure of why this is. Street cars that would benefit from a non adjustable type hydraulic setup would be the MOST likely to be driven in traffic at low speeds more than a dedicated drag car.