Valvetrain weight vs. RPM limit

OK I know there is no clear cut answer on this but I would like some opinions. Lighter valvetrain equals higher max RPM without valve float so.....how much does it really matter? An example: A small block with some normal replacement stainless valves, locks and steel retainers against 5/16 stem stainless valves, lighter locks and some TI retainers. Both have 136 seat and 340 open pressure. How much RPM difference do you think there would be? Also both heads have the same rocker arms, pushrods and solid flat tappets. One last thing I've been running locks with recess for lash caps but don't run lash caps for 2 years now and I'm curious if I'm the only one. There is a small weight difference between the two and the cost was the same so I said what the heck.