Pear::DB sucks? OK, what ever you do don't site reasons. Error handling has been addressed in part by PEAR and even better with the new PHP 5 that is in beta. Try that and you'll refute your own comment related to error handling.
PHP disadvantages are:
- No control over threading
- Code not compiled
Other than that the only real difference between Java and PHP in terms of scalability is in EJB's.
Now what people should do is talk about cost of development. Most Java shops are using for-profit app servers (websphere, BEA, etc). Then you have the cost of Java developers and the relatively steep learning curve.
Fact is, both have a place in your IT shop. The question is do you have the knowledge to know when one makes more sense than the other?