lazy programming by website developers frequently causes crashes nowadays That's a bit harsh. Netscape 4.7 has bugs which cause it to crash on valid CSS. I don't think you can blame web developers for that if their code is standards compliant.
I'm quite conservative about web design and supporting older technology, but I'm less sympathetic when that means supporting old bugs in little used software. If it validates at validator.w3.org and looks right on IE, Firefox, Opera and Konqueror it's good enough for me. I'd test on Safari too if I had a Mac.