Without sedation, it's not exactly painful (though if you have active pouchitis or cuffitis you may experience pain), but there is a lot of pressure from the air that is pumped in, and it is certainly uncomfortable. The first thing I always want to do when I'm done is run to the toilet to expel the air. I also felt a bit of a pulling sensation when they did the biopsy, but again, it was all bearable and it's over fairly quickly.
That being said, it should be your choice whether or not to have sedation. Don't let your doctor pressure you. To be honest, I've come to prefer it over time and multiple scopes (I've come to a point where I just don't want to feel things anymore), but I always base my decision on how I'm feeling leading up to the scope, the reason for the scope, and to a lesser extent, what I have planned for the rest of the day. It's not often I get a day off work, so if my scope is early in the morning and I have the rest of the day off, I may opt for no sedation so I have the rest of the afternoon to goof off.
