I just joined and I'm very excited about this swap! I love stuffies/amigurumis of all kinds. Seriously, you should see my collection of all things stuffed. It's insane! My kids have begun to follow in my footsteps, too.
I think for super detailed things, it's best for them to be big (at least in crochet). If you're going to crochet lots of different pieces or clothes to make the character look like it should, it's hard to fit all that in a 5 inch space! I usually like to make my ami's at least 12 inches or so. That's not saying that I wouldn't enjoy an adorable 5 inch stuffie, though! I think as long as it's made with lots of love, it will be great!