Restraints getting tighter mid-ride can happen on any Eurofighter or Infinity in my experience, irrespective of the restraint type chosen. Whether that happens to enough of an extent to be uncomfortable seems to depend on the ride layout/forces delivered.
I fully agree with John about the potential for Smiler with lap bar trains to be horrible. I find the OTSRs tighten noticeably during the ride, but the lap bar trains also have the seat tilted back with a pointed front edge that attacks the other side of your thighs too. It's not pleasant on Karacho, and massively takes the shine off Karnan.