IMHO, the biggest difference between 35i and 35is are "ego" and "price hike" for a non-M car. The 35is brings a lot of it, as if it it were trying to compensate for some short comings......
Both cars are tunable!
As for the "antiquated" manual transmission, I've test driven DCT and I "personally" don't care to buy a car that makes "me" feel like I'm playing a Playstation video game by pushing and pulling buttons.
The only thing I liked about the 35IS are it's shoes, which I stole.