Hi,
The RX is a great throuble-free engine for sure , and used world-wide with great success ... Several combination of set-ups (prop-fuel-pipes etc) works on this engine ... It`s very tolerant ..

The original bearings have worked just fine for me, 200-250 flights interval ... ( 2 engines for about 800 flights )
One thing ,in my opinion, that makes a different how long they last ; is the "everyday - storage" of the engine ...
I set the prop at "top-dead-center" and the throttle fully open so there will be ventilation from the crankcase ...
The nitro seems hydroscopic and absorb water that attack the bearing (rust) if not ventilated ... I have been suprised how quick this process goes ....Just small nicks caused by rust, can soon wear down the bearing ...

some proposal;
* 2 headgaskets
* OS-F plugs
* 15/15 fuel
* Hattori , mac headers
* Hattori , ES pipes

Just mine experience ...
Kjell Olav