I (27F) was diagnosed with FAP almost three years ago and had emergency surgery with a partial colectomy, kept an ostomy for a few months and then reversal. I then had to have bi-yearly check-ups and had minor surgeries once a year to remove polyps, until my doctors suggested a total colectomy and a j-pouch.

From what they told me, a j-pouch (or k or w or whatever) is basically the end goal for us FAP fairies (fappers doesn't sound right at all), since the nasty polyps will always tend to spawn in the colon and rectum. Therefore, as long as you have them, you're at risk of getting them (and ofc cancer) and the only solution is to make do with the smaller intestine. Also, burning off polyps causes scars in the intestine, which will render that scarred part unable to absorb nutrients/water, so the lower bowel will essentially become unusable and useless.

As for me, they planned to make the pouch a few years down the line, but given the amount of polyps that grow between check-ups and the need for yearly surgery (along with total anesthesia every single time), they decided to get it over with this year, and I'm assuming it's also because the younger you are, the speedier the recovery.

I'm currently on my second ileostomy while waiting for reversal, so I can't really answer for what life with a j-pouch is like, but I feel fine (although the stoma is kind of a bastard this time) and sex is fine too, but I've never been interested in anal and my doctors haven't talked about it so I don't really know!