"Don't use ORMs"? I'm sorry, that's just plain wrong, or you were exposed to the wrong ORMs. Doctrine2 has great scalability - it has all sorts of caching built into it - result caching, query caching, and so on and so forth. It's actually -way- more scalable, and easier to develop for, than writing raw SQL (which, by the way, is a portability nightmare).
Also, if you want to use a decent MVC framework, not using an ORM would be quite dumb.
And if you're not using a good, modern, scalable MVC framework in this day and age, well, I pray for your soul.
Every layer of abstraction you add, not only adds a layer of complexity and extra points of failure, but also adds restrictions.
By definition, an abstraction is more restrictive ... otherwise, you're not really abstracting anything.
If you're making a simple web app, an ORM is just fine. If you're building enterprise-level software, it is a really really bad idea. Half your code will be using it, the other half will be forced to use half-assed SQL queries that try to fit into your ORM. Because, quite simply, you will need all that SQL has to offer to make things work right. You can't afford to abstract SQL away. Trust me, I tried. In the end, the best you can do is go with something like LINQ.
I built a LINQ like system for PHP a while before Microsoft did it for .NET =)
On a side note, I would also stay away from all the frameworks and build one yourself. If you're on a long-term project, it's worth it. You'll understand what is happening and what each call really costs you. You can also refactor an existing framework. Either way works.
I can't stand the 'portability nightmare' comment/sentiment from ORM (ab)users. How often do you swap out your DBMS from MySQL to Oracle to Postgres? Writing SQL should not be anathema.
I agree. We use our own lightweight ORM at Twitpic (similar to PHP ActiveRecord). It produces SQL for you unless you feed it your own optimized query, but "does the right thing" 99.9% of the time.
IMO, "ORM produces bad SQL" is a myth and more often a case of bad indexes and not bad SQL.
So, USE AN ORM!!!