It was no.3 that eventually killed Gentoo for me. Took a three week holiday and it must've been a busy release period or something, because when I came back I had an unholy hell of packages needing updating.
The worst part was there were multiple dependencies that just wouldn't compile. I fixed the first couple, but when you have a 3hr+ OpenOffice compile fail on you inexplicably... I just want my computer to work without worrying about all that! It used to be that people would say "Then why are you using Linux? go back to Win/Mac", but nowadays a perfectly stable, maintainable and fast Linux is easily achievable. I think this is the major reason behind Gentoo's declining popularity recently.
Having said that, I learnt a huge amount about Linux just by unbreaking all the bizarre things that risky Gentoo emerges did to my system :)
Ultimately, it all comes down to how I'd rather spend my time. Hours and hours every month running a big emerge on Gentoo, or a few seconds in pacman on Arch? I have work to do on my computer and eventually the process of just running the Gentoo updates was occupying too much time that I could be spending on actual work.