That one are made with ASP.net. Elgiganten are using an Apache 2 server, so they got a caching server or it's made with PHP. Dustin dosen't say what platform they are using. But their infrastructure are mainly Microsoft, so ASP.net are a safe bet.
I haven't worked for any e-shop customers. So don't know if they are based on CI or not. That's not something you disclose.
Just had a quick look at the site and here are some thoughts:
* immediately wanted to know my location.
* slideshow are too jumpy. Needs to fade between images if you are going to keep it.
* blog? Why do you need that?
* images are to big one your startpage. Looks good if you search for something.
* "What Roynac's Clients Say?" Have a link to e.g. trustpilot instead.
* can't press ESC to close an enlarged image
