I personally like the non-gated pulse turbo for 2 reasons, less cylinder pressure at low engine speeds, and the fact that max power is directly controlled by your right foot. A wastegated turbo brings on boost quicker, creating spikes in cylinder pressures. A wastegated turbo also bleeds off energy, which somewhat limits peak power potential. Most say 10-12 psi is max for an IDI. I disagree. If you're making that boost at or around 2,000 rpm, it's harder on components than at 2,500 or 3,000 rpm. I've run 15-18 psi into a 6.9 with a Banks non gated turbo between 2,500-2,800 rpm for extended periods and never had a problem, hardly any smoke, and relatively decent economy to boot. I've driven a few factory turbo trucks as well, and they didn't feel as peppy at those speeds or rpm, and got slightly worse economy. All trucks were 4.10 equipped, running ~65 mph in direct, and grossing 18-20k lbs combined.
I've noticed a tendency for people to 'lug' an engine more with wastegated turbos, creating higher pressures and temps than necessary as well. There is a reason these engines are making max power at 3,000 plus rpm. They were designed to rev up more than inlines were. Low torque peak gets you moving better, while the broad powerband ensures you stay moving. You're best towing performance is honestly around 2,200-2,500, almost dead in the center of the powerband. Power under that from a wastegated turbo really isn't useful for much other than being ******* parts.