The intake on our cars is however somewhat flawed....
Flaw #1 - Inside the intake box is a long snorkel in the centre section designed to reduce noise. This also reduces airflow as the entire surface area of the circular filter is not exposed and instead only around 30% of the surface area is actually able to flow air through it. It also acts like a straw and sucks up water if you are very unlucky and fall foul of Flaw #3.
Flaw #2 - The plastic pipe that feeds cold air from the area near the centre upper location of the front grill, just in front of the radiators is extremely restrictive and significantly less diameter than the 80mm MAF and pipe to the turbo. Any gains in the flow of air from changing this will be massive but heat soak issues need to be accounted for in the design.
Flaw #3 - Said pipe from above has a habit of coming loose where it connects to the base of the intake box allowing the car to ingest water when driving through no more than 6" of water causing hydro lock and costing several thousand pounds to fix the resting damage to the engine! search the forum its a known issue that has cost people a lot of money.
Aside from that a K&N filter is just inherently better at flowing air so is always an improvement over a stock paper filter as demonstrated in this old school test:
https://www.youtube.com/watch?v=aKKn38nmXtg
In terms of damaging the MAF its true but only if your a knob. The filter has to be maintained and a filter recharge kit is needed:
http://www.ebay.co.uk/itm/K-N-Recha...arts_Vehicles_CarParts_SM&hash=item43cc2ae3be
Every few thousand miles when you would normally change your OE filter you remove the K&N one, jet wash it with the cleaning solution, then re-oil it. If you put too much oil on it you mess up the MAF. If you do it properly, its fine!
I have had a K&N on mine for 3 years and its been recharged twice. I have also removed the snorkel inside the airbox (flaw #1) and ensured that Flaw #3 is avoided by getting the pipe seal perfect with plumbers silicon tape!!
In terms of next steps, I will replace the whole intake unit with a direct induction unit, most likely candidate is a Maxogen cone filter. This is due to adding a very large Front Mounted Intercooler that will mean the air feed pipe from the radiator area (Flaw #2) has to go exposing me to severe risk of Flaw #3.
I will avoid the heat soak issues by installing the cone high up in the same location as the OE intake, although this will expose me to potential hydrolock issues in 10-12" of water so that will either have to be avoided or the alternative location employed.
The alternative location is in the engine bay itself. This is a worst case scenario and would have to be accompanied by a lot of fabricated heat shielding to deflect engine heat and supported by a cold air intake pipe from wherever I can fine cold air, likely near the location of the OE air box to feed cold air up through the hole where the old intake pipe went into the engine bay.
Its a work in progress so i'll let you know how it pans out.
In answer to the OP's question, yes get a K&N. A lot of us on here have.