Does Safari have this feature?

By default, no. However, there is an absolutely astoundingly good app called AcidSearch that adds this feature and more to Safari.

I'm sorry I can't answer the Opera question, but I'm not particularly experienced with it. Firefox and Opera are both available for OS X, however, and they both work very well. In fact, Firefox for OS X is considered to be better than Safari by many people, so don't limit yourself to just Safari because it's the default browser.

 

Safari has a Google searchbar in the toolbar. Much like FireFox, well Firefox for Mac anyway. There are also third party apps available that will allow you to use Yahoo!, IMDb, etc etc.

You are aware that Firefox is available on Mac as well right? I'm sure most of the extensions will be as well.

You really need what? What features are you dependent on? Comparable in what way?

I have to admit I'm slightly confused as to what the crux of the issue is.

 

Get firefox. Install plug-ins (Google the GrApple Brushed theme). Then, FF looks like this... and is pretty freaking sweet. As well as being the super-extensible browser you're used to.

 

For the Safari/Opera thing, you said you're a web developer, so from that standpoint, no, they are definitely not like each other. I've run into plenty more bugs in Opera than Safari, and personally, it's easier to code and fix things for Safari than for Opera, since Opera isn't generally used as much as Safari.
-Chase

 

Saft has this feature - but I still prefer Firefox because of all the extensions.
Saft is really cool though - check it out.