<p>I have been playing with Haml recently and really like the way the resulting code looks to me...the developer. I'm also not too worried about a designer being able to consume or change it...we're a small team. </p>

<p>That said, beginning work on a project we believe will generate quite a bit of traffic (who doesn't?). I'm concerned that there are things I just don't know about haml. Is there anything erb can do that haml can't? Does haml have a negative effect as a project grows? Are there other things that should be considered?</p>

<p>And finally...how does Haml compare speedwise to erubis? I see that it supposedly beats erb and eruby now...</p>

<p>Thanks!</p>

I would personally recommend us erubis in precompiled templates.
Especially if there's no need for dynamic templating. Then your biggest slowdown will be limited by the speed at which ruby can parse ruby.
I'd probably set up a small cron job that just monitors for changed source templates and autocompiles them on-change that you can turn off when not in use.
Compile once, use many.
Oh, and if you're really concerned about speed, Tenjin may be worth a look too ( same creators as erubis )
http://www.kuwata-lab.com/tenjin/rbtenjin-examples.html