No, there should not be a difference, it's just harder to actually see directly what your changes do when you have to go through the process of starting with HTML and tokens, then placing the property settings in a seperate XML file, then parsing the skin.

By the way, you can even put .ascx type code directly in your html skin if you want.  The parser will just move those over without touching them.  So if you ever feel like it may be easier to skip the XML file for a specific SkinObject you can do that too.

Another nice aspect of working directly on the ascx files is that you do not have to upload to install them, just copy them to the portal skin folder and you are good to go.  This is really handy when you are trying to get everything looking just right, you can work directly on the skin and see the results in a browser instantly.

Typically, I will:

• Layout a look and feel in Photoshop
• When I like what I have I will then break that up into html (export)
• I rename the file and drop in in a skin folder in DNN and build a skin.css
• Cut and past the control registrations, set the panes and put the style information into css.
• Paste in the control referrences where I want them on the skin
• Add the skin to a page in a portal to test
• Adjust as needed until I get the final look

Done..   I often use Visual Studio 2005 or Expression Web (until the next version of VS comes out) to edit the file and css.

It is nice working direction on the skin with live view in DNN as to the results.  If you use html files along with the addition xml file, you have to upload them to the portal for testing so that it can convert them to the ascx file.