with the cam cover one.. put simply they fill up. real fast. so instead of a "steady" stream of oily fumes comining out, you get no oil coming out and when it fills up 2~3 laps all of a sudden you get masive surges of oil being pushed out and doing harm.
the second one is good but just not big enough.
ive had all sorts of issues with catchcans on the track. i ended up making my own one. it holds about 2 litres. and ive evan combined the power steering resovior with a breather so it to doesnt overe flow everywhere.
tested at wakie it worked a treat. no more engine oil over one guard and power steering over the other lol. il put up some pics soon.