There is an excellent article in #56 Aug 2003 of the Oz 4WD Monthly, if you have access or collect. Recommendations are 100,000 for a service with IDI nozzles and 150,000kms for DI nozzles. Recommendations for rotary pump service is 250,000 to 300,000 kms (though much depends on service issues/filtration etc), and no mention of inline pump service that I saw. Article focused on filtration as the biggest thing you can do for your pump and injectors, (water and particulate handling).
Direct quote...talking IDI nozzles here: "As the injector wears, the pressure it sprays at drops, until eventually it dribbles the fuel out rather then squirting it. The result is poor atomization of fuel, which is then forced to burn closer to the injector, causing the nozzle to overheat and melt away. The extra heat generated weakens the spring's tension compounding the problem. Usually the performance drop off is so slow that drivers don't notice...."
Talking with local injection shops I have learned that DI nozzles do not take the beating IDI ones do, so in many instances the nozzles can be sonic cleaned, checked and if okay put back together, and shimmed to crack at factory specs. IDI nozzles on the other hand usually need to be changed out, and shimmed.
Benefits would be knowing your injectors are healthy, and working correctly, meaning better use of the fuel.
Many injection shops will take your used nozzles to the test bench and show you the spray pattern and crack open pressure. Use the FSM to guide you through the removal and installation process. A deep socket will work to take out your old injectors.
hth's
gb