I went for a drive with the 35is + AR catted DP's to test the sound once warm.
NB: the 35is exhaust is a lot louder than the standard 35i exhaust so I cant comment on that - the 35is exhaust is more like the 335is version but not quite as loud.
Now with my car (stock 35is exhaust) and catted AR DP's it sounds farty when cold that is for sure. When warm there is only a slight rasp at mid-high RPMS at full throttle that I can hear when I drive close to another car or wall.
Here is a very good vid of the actual sound of a 335is with stock exhaust and catless DP's - the rasp is similar to what I get but obviously much more pronounced with the catless.
Here is another vid of a 335is with catless DP's. Not such a good vid but when he goes WOT in the second part of the vid you can actually hear the terrible rasp @ 30secs (although some love it ...I don't) as he goes thru 1st and 2nd gear.
And I'll say again the 335is exhaust is similar to the 35is but a little more aggressive.
Catted definitely smooths out that rasp. Decision is up to you. Sound vs a little more power.