I have an electric clutch on my 10 year old 430 JD and I have never replaced the clutch. I always engaged it at an idle when I used to mow with it, but it's diesel so it has enough low end torque to do this at an idle. It sure seems like a lot of jolt to the whole machine to kick the clutch on while the engine is screeming full rpm's.
If your manual says to do this at full rpm's, then I guess you should. Sounds to me like they just want to sell you parts for it. An electric clutch should engage at an idle just fine if you have enough torque to power it. 2000 rpm's should be plenty of speed to start up the blades, but bring it down to an idle before shutting the blades off.
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^One of the lawns we mow