Very cool website, I hope you don't mind, but I am going to be really picky as you asked,
I would avoid large panoramas on the opening page of your website.
Try making the file size as small as you can while still offering reasonable quality, but then have no fullscreen option.
However if you want the fullscreen option you may consider using multi resolution so when the fullscreen button is clicked the quality increases.
Also I noticed that in your Portfolio, all the panoramas display the splash screen to tell the user how to navigate the panorama. This happens every time you click a thumbnail and can get quite annoying.
Also in the portfolio page the panorama to the right, the load bar is not centred, it is a little to the left.
For the HTML5 I would make sure that you have the double click toggle fullscreen option selected, this can be found in the Advanced Settings tab of the HTML5 output. When I navigated to your site with an iPod Touch 4th generation which has the same size screen as the iPhone 4, I could not centre the display, the double click fullscreen option would then make the panorama fit the screen.
When you navigate to your site with said apple device and the HTML5 version is displayed, double tapping and going fullscreen means you would not need the small text and the Apple device images for the iPad/Phone. They are to small to be read in any case. Perhaps some text in the HTML5 skin saying, Double tap to fill the screen. Then you could give the text the actions, Enter Fullscreen => Set Element Scale to 0 , Exit Fullscreen Set Element Scale to 1.
All the very best.