It’ll be a hassle downloading the site, adjusting, rechecking, etc but I shouldn’t have to do that too often – hopefully.
With iWeb if you publish via FTP, it will only publish changes you have made. This is the major drawback to publishing to a folder, where it publishes the entire site each time. So if you are wanting to check your pages on your local machine this is a little bit of a hassle.
There is a pretty easy way around this, however. Each mac has Apache web server installed. You can set up iWeb to publish to your "local" webserver via FTP. Once you do that, you can access the site using the standard local host addres ... either enter 127.0.0.1 as the address, or simply type localhost.
This way each time you want to check things in a browser you publish the site, which will only have to update changes, and then pop over. It's actually very fast.
There are basically two steps. First you turn on your local webserver in the sharing preference pane.
In iWeb, set it to publish to FTP Server. The site name is Documents (which is the default folder name for the local host).
In the FTP server settings, the server address is localhost. The user name is your account name for your mac followed by your password. the directory/path is /Library/WebServer and the Protocol is FTP. Once you have the FTP server settings setup, you should be able to click the Test Connection Button and it should let you know it succeeded. If so, you're ready to publish the site. The first time you publish the site it will tell you the folder Documents already exists and ask if you want to replace it.
Once it's published just enter localhost in your web browser (or IP 127.0.0.1). As I said the advantage is you when you publish from then on, only your changes are published. This usually takes only seconds if you have just modified a page or two.
This actually works with most web development tools. You can in fact enable virtual hosts for the local host, meaning you can develop a multitude of sites and access them each individually on your local machine.
Once everything is ready to go, just change the configuration to upload to the actual host.