I should think that the OTSRs require less mechanism to restrain guests than a lap bar. Also, is it true that Gerstlauer's Infinity lap bars are sort of like the clam shell lap bars on B&M Hypers? If so, then these would have made Smiler a brilliant ride! The clam shell restraints on Mako at SeaWorld are the most comfortable restraints I've ever sat in! Although, in Alton's defence, the Gerstlauer OTSRs are probably one of the more comfortable sorts of OTSR I've ridden in. Not up there with B&M's OTSRs, but better than if Alton had put the Intamin OTSRs on it like the ones on Rita and Colossus. If you put those on your ride, then it won't age well. For reference, both Rita and Colossus are awfully painful, and I actually found Cheetah Hunt very, very rattly with these restraints when I rode last year.
Anyway, back on to Smiler. I definitely think the ride is less smooth now than it was in 2013. I do find the Smiler to have quite hit and miss smoothness depending on where you sit. In the front two rows, for example, I don't find the ride anything more than rough around the edges. But I did have quite a rattly back row ride once. Also, when I was looking back through this topic, I saw the original concept art. And personally, I prefer what we got to what was shown in the concept art. The concept art looked far too dark and dingy for the vibe they wanted to go for. The hexagons in the original pre-lift section looked cool, admittedly, but the rest of it looked a bit too, um... full-on mental asylum for the vibe they were trying to go for. The pre-show(?) room in the original concepts looks far too run-down for the happy but creepy vibe of the Smiler. The lower exit section in those pictures vaguely resembles a plastic bag tunnel to me, which is far, far lazier than the fun illusion-filled exit we got. I still get quite disorientated walking off the Smiler, and I've been on it many times over the last 4 years!