I have no problem with my Pi set to 950MHz. Some claim to have got theirs running at over 1200MHz.
Overclocking may shorten the life span of you Pi by a few years - maybe even reducing its life from 30 years to 25 years
What he said. You are not going to shorten the life of your Pi by overclocking in any real term way. So overclock as much as you want (as long as its still runs!).
Note that due to variations in SoC manufacture, some will overclock a little some a lot, I've heard of one at 1.2Ghz IIRC. But that does void the warrantee bit.
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
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