Currently, IMP.helpers is only one .h and one .cpp used primarily by restrainer and has now interesting external dependencies. If they are not used much outside of restrainer and there are no plans to add significantly more functionality, I think it might make more sense to move them into the restrainer module. Adapting existing code would be trivial (simply replace IMP.helper by IMP.restrainer), so the cost is small. And reducing the number of modules is always nice.