I think you have misunderstood my examples.

> For border radius, if you were stung by the change, you would had to have been using the vendor prefixed version of the property

The rounded corners issue I talked about wasn't a mark-up issue, it was a basic rendering bug. It took several attempts to fix, over a period of months. During that time, any sites that used even simple rounded corners with an unfortunate combination of colours would get a horrible show-through effect or at best a poorly anti-aliased rendering in Chrome.

Rounded corners were surely one of the most anticipated CSS3 features, just the kind of thing where a rapid release cycle is supposed to move the web forward according to advocates, and they regressed it, badly, for several months.

Moreover, as long as Google and Mozilla keep releasing "experimental" CSS features with syntax and capabilities that aren't yet standardised, they are on a path where the only options are supporting alternative, non-standard functionality indefinitely or breaking existing web sites that were written using the experimental features at some unspecified point in the future. That's starting to sound like IE vs. Netscape all over again.

> For the video element, you might want to actually test for a bug before claiming to have been bitten by it: h264 support hasn't been removed yet.

Google dropped support for H.264 in the Chrome development builds some time ago, and the change is scheduled to be pushed to users of the official release imminently.

> Meanwhile full adblockers have existed in chrome for some time, and while tab isolation has been somewhat delayed in firefox, plugin isolation has done wonders for total crash rates.

If you've got a full ad-blocker for Chrome, I'd love a link. I've never found one anything close to as capable as things like Ad Block Pro in Firefox.

As for tab isolation in Firefox, it's not just a robustness issue, it's also a performance and potentially a security issue. One tab loading slowly or running screwed up JavaScript can still block your entire browser for several seconds, which can be very annoying.

> Stick to core functionality -- which I think you'll find all the vendors have done a great job at keeping from regressing -- and you'll be fine.

No, they haven't. I have given you four specific examples, and while you could argue that the two Chrome ones (CSS3 rounded corners and HTML5 video support for H.264) were experimental, there is no denying that the two Firefox ones (Java applets and the basic typography engine) are fundamental, well established, and seriously broken in several recent Firefox 3/4 builds. Please check my posting history from a few weeks ago for details; I gave specific citations to the last guy who seemed unable to believe it.

Of course, if you're going to argue that we shouldn't worry about any problems with experimental features, particularly either regressing them or cutting off support when a standardised alternative becomes available, then you're basically undermining the entire premise of this discussion, which was that rapid release cycles advance the web more quickly. As I've been saying for a while, I don't think going back to the race between IE and Netscape is going to advance the web for users in any useful way. It's just going to create a nasty, half-defined mess that most developers are going to ignore most of the time anyway, and that breaks things in user-visible ways the rest of the time.