At the risk of starting yet another ... discussion ...
I seriously considered the new Chevy I4. As you mentioned, it's meant to replace the v6, not the 5.3. According to the GM forums, I have yet to read a really negative review from owners (note, "owners"), it is apparently a great engine when expectations are in line with reality. It tows really well (in terms of power, I think they just bumped it up to 9000+ pounds?), and can get pretty good gas mileage. It's not just a car engine that they threw a turbo on. They designed it like a diesel in terms of block, crank and connecting rods, and power delivery; it's built and tuned first and foremost for truck duty.
For normal everyday usage, the worst part would be the sound. The reason I didn't get it is because of my extensive trailer towing, and because Chevy dealers wouldn't work with me in terms of price.
It's certainly not a "manly choice", but I couldn't care less. Most of that is ignorance and swagger. How does it actually perform (very well!) and how does it last (yet to be determined).