I too have flown some of these NYC escape routes (always to RDU in my case). Most recently on a EWR-RDU flight about two months ago. We did finally ascend to a higher (normal) altitude on my last one. In a window seat it can seem a little concerning to be so close to the ground for so long. In all cases, the pilots gave a PA announcing that we’d be flying an escape route. Otherwise I could see people getting freaked out.