The best CSS/HTML developers should be like this — if you deal with fixing bugs in IE enough, you start writing code that prevents them in the first place while still looking awesome in standards-compliant browsers.
Happy to say that I'm one of those — the day I discovered I could do this, I felt like I leveled up.
In addition to memorizing the rules, you'll also memorize the specific IE bugs; see a page in IE all messed up, and be able to go, "Oh, I know what would cause that," and be able to fix it without spending hours tracking down the bug.
Comet in IE6? Can you elaborate a bit? I recently had a need for a comet thingy (but not cross-browser compatibility) - so I made a small solution with x-mixed-replace. I don't even know where would I start with IE6, since even later versions are their own world.
Long polling is possible in every browser ever, basically.
In my case, it was less intermittent events and more low-latency streaming data (position/GIS stuff), so I went with the forever frame. It really is splendid for pushing data to the browser without the nasty lag.
