Depends which duration your looking at? A longer duration like 270-280 and up, will start to give a rough idle, and poor low end performance. You would also need further work to get the full benefit (worked head with bigger valves, exhaust manifold, etc etc). Perhaps you know all this from your searching ....
The only useful info I have is my experience, on my otherwise standard digi, (besides a cone filter):
I spent a while looking at specs, before getting the mildest kent cam (266 duration), it was also (happily), an ebay bargain! I checked the standard cam duration, its about 220 something if i remember correctly. I wanted to maintain power throught the rev range, as I dont ring its neck all the time, but wanted to help the engine produce power more progressively towards red line, rather than tailing off at 5500rpm ish (primarily to help overtaking). From what I gathered in my 'research', the same lift duration can have different effects, depending on where the lift occurs. i.e. more lift before or after TDC, effecting where the power band lies. So I was pretty happy that the cam i chose was the best for what i wanted. But have a look yourself, and see what sort of spec suits how you want to drive the car.
Performance has improved, but not to a staggering degree. Idle is slightly more lumpy, but relatively smooth. A bit burbly. Low end power remains, it will pootle about town happily below 1500 rpm in 3rd, pulling away fron stationary without the need for any more clutch than standard. Mid and upper range power is slightly improved, and it feels like peak power arrives a little further up the rev range with a few more horses. So all good. Hopefully it will allow further improvements when I get a 4 branch on in the near future.
