Yes, apparently there ARE many right answers.
I did a search using your link and a very quick look found the following ones:
1) You can run 4-ohm speakers on an 8-ohm amp, no problems.
2) No you can't, you'll overheat your amp.
3) If you're careful you'll be fine.
4) Put a 4-ohm resistor in series into the speaker wire, works fine.
5) No it won't, it'll still overheat the amp. (Or the resistor.)
6) Put two 4-ohm speakers in series on the same wire pair.
I'm glad I got that cleared up!