I'll confirm that a catheter was surprisingly no big deal pain wise, at least not for me. We're a little nervous about anything going on down there, and tend to overestimate the pain.

On the other hand, a suction tube being pushed down through my nose into my stomach is the worst pain I've ever experienced, and it took them three tries (the first two hit my lungs). I have a high pain tolerance, but I needed half the nurses on the floor and my spouse holding and calming me to get that into my stomach (you have to be awake and swallowing rapidly, with no anaesthetic, to help guide it the right way).

YMMV