who is running MRL (BAM) Lifters without lifter bore sleeves

Duane are you talking about "durability" on a Hi rpm race engine or a Lo rpm street engine that may see 6000 rpm on rare occasion?
That's exactly the point. I have not seen many on this thread state what they are intending with the motor. IMHO the guys that are having oil pressure issues is because you did not plan the build correctly. Like Pittsburg racer said earlier, you should really never plan to run any kind of roller lifter in a La block without either tubing the galley or bushing the lifter bores. What kinda cam lift. How much spring pressure. What rpm range etc.
In a mild street build I personally do not see the reason for a roller lifter. IMHO.