so why excactly does porting reduce reliability and increase wear, after all you are only letting more air in and out of the engine, and only a slight increase in load on the engine

its the next step on my mc28, but its more of a street bike then a track bike, although i do hit the track about once a month

You've just answered your own question.

Tuning gives more power. This of course stresses each component more, causing more wear, so reducing reliability.

Try running instead of walking and I bet you need to buy new pumps sooner

Running, thats such an ugly word.

When increasing port size this affects ring life and reliability as the ring is held by less barrel, the ring of course wants to jump out so wears each time it passes a port. If you look at a nsr exhaust port and compaire that with a RS one you will see the top of the port is almost flat on the RS. The curved top of the nsr port gives the ring a much easyer life at the price of peak power.

Just look at what a ring has to contend with half way down the stroke. At one stage its over all the transfer ports, the boost port and half the exhaust port and being suported by what equals too bugger all. If you make the bugger all even less that poor ring has one hell of a job to keep itself in one bit and not thow its self done the exhaust.
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If I have to take the carbs off once more...