I'm not a professional plumber, and I'll share with you the rule that I use when I decide whether I'm going to get a pro in for a job.

If I'm not 100% confident that I can do it myself, and if it's something that is going to leave me without working plumbing until I finish, I get the pro.

I'm willing to live without a single sink or toilet working while I take a couple days to figure things out and get the right parts. But I'm not willing to completely disable my home's plumbing for days. That's just not worth it.