I've noticed the same thing on two machines - TiBoook 500 and D800/G4. I'm really liking the new OmniWeb 4.1sp3. If they can get the speed up and improve stability, they got my $30. It's definitely the best looking browser out there...
The new Mozilla is getting really close too. It's pretty stable, very compatible, but 0.9.5 seems to render slower than previous builds for me. If they could get speed up, it could be my everyday browser, but I'll probably go with OmniWeb in the long run. It rocks...
Just about every browser currently under release for OS X is missing something. My personal site is a great example of this. The site itself merely abuses some neat DHTML tricks that work within any Standards compliant browser, with DOM support, or an IE implementation, however, each browser in OS X responds to it differently.
1.) IE 5.1 - To use Layer masking, you have to enforce a height within your span tag, otherwise, the Talsman engine just blurs out any text below the initial render. Hence, I have to force IE to load a 30000 pixel height layer, just to make sure it properly scrolls my text. Annoying.
2.) Omniweb - OmniWeb will at least render to proper layers, in correct position, however, it's DOM support still lacking, I can not capture Mouse events yet, meaning the scroll bar doesn't work.
3.) Mozilla - my site seems to overflow Mozillas window buffer, forcing the window to close.
However, IE 5 and above on the PC render it fine (not nearly as beautiful as OW does, but, eh, what are you going to do ). It use to work in NN 4.0.8, till I broke it on purpose. Hence, I'm forced to shuffle browsers constanly under OS X. That, and the annoying " I'm going to use IE not matter what you tell me!" bug, which still exists in OS X 10.1, and, web browsing is sadly, a hit-or-miss situation.