You're gonna' be hard pressed to find an opinion from folks who have tried both systems, since the vast majority of people pick one and stick with it. These things aren't exactly cheap, are they? I can give you one data point though.
I fitted a pair of Ragazzone rear silencers on my 2.2 Spider. It's a TINY bit louder, but not much. I can't tell the difference with the radio on, for example, unless I REALLY thrash it. They're plenty quiet for civilized driving. A business associate or client would not comment on the exhaust note and probably just figure that's they way they build cars in Italy. As far as I'm concerned, they were not worth it considering how much they cost.
In fact, nobody here in Italy has ever made mention of my Alfa exhaust note either to say it was nice or too loud. This is NOT true of my Ducati motorcycle which is fitted with a pair of spectacular sounding Termignoni silencers............. well, "silencer" is not exactly the right word ............ more like attractive stainless steel display points for the Termignoni decal .......... "silencing" is not their strong point.