I've been using the beta for about a month and the "gold version for about a week" in classic mode. I still have noticed loading time seems to be eternal... Once up and running, I have no complaints.

Netscape 4.78 for Windoze and Mac OS 9.1 is another story entirely. If you ever use Composer for quick html docs, you may be watching NS bomb on you frequently. It's not catastrophic... Doesn't mess with your system, doesn't "leak" memory and you simply have to double click NS again... But the problem is so reproduceable as to be an obvious "undocumented feature" that should have been noticed if any testing at all was performed.

But, I digress... Your question was about the beta and if you can dump IE... absolutely. I've never used IE on my Mac (okay, a few months for testing) and don't plan on it. Out of principle...