The pro's of that are that you develop directly into a setup that is comparable with the real deal and issues that come floating to the surface will also do in the production environment.
Second, a finished product just needs to be copied to the production server to simply work.
Third pro is that when you use a development environment you simply do not need an IDE, a relative simple editor with syntax highlighting and snippet management will suffice.
The downside of IDE's are that they tend to make the development road overly complex and most have their own quirks so you have a relative steep learning curve for that and it's hard to switch so you are more or less jailed to a particular IDE.
All this time on learning your IDE and learning to deal with it's quirks are better spend on your web project.
It has a bit of a learning curve, but it feels pretty productive once you get used to it, especially when taking advantage of it's many plugins. It's not for everybody, but be sure to check it out, along with some of its tutorials on the web.
Normally people go for a fully featured text editor, with at least syntax highlighting. Macs have a ton of options (Textmate, Kod, Dashcode, etc).
On Windows I use Notepad2 or Opera's edit source. I find Notepad++ awful. This may be of interest to you http://en.wikipedia.org/wiki/Source_code_editor .
Overall, I'm left with the impression that it's "a mile wide and a foot deep".