'Some' days search results are not good. I've found that myself. But it does not usually last too many days. Sometimes just a day, sometimes a few.
Changing an ultrapeer will not necessarily do any harm however. Some ultrapeers may not be handling messages very well. Two reasons for getting rid of old version ultrapeers ... one is many spam ultrapeers use older versions. Another is, with the older versions a person could 'cheat' into becoming an ultrapeer .. when their LW is not behaving well enough to really be an ultrapeer. Thus giving poor ultrapeer responses. Perhaps because their uploads & downloads are saturated.