I would like to start by saying that the trend for websites (and a trend that many believe will quickly become the norm) is to be completely responsive design. Besides the fact that it is just plain awesome, it is much more compatible on the many devices used for surfing the web, and will be less maintenance as new devices are developed. That said, CGI driven mobile commerce is much easier to implement, has less bugs and is less expensive.
Now to the nitty-gritty.
Responsive Design. A web page where the browser width changes will change the look of the site. You are not sent to a different page; A new page is not created for you. You stay on the same page, with the same code, it just looks different width different widths. Below is an example. You will see that there are 6 navigation links on the full version, 5 on a typical tablet, and 3 on mobile. You can also see that on a desktop and on a tablet, there is a banner image (slightly different sizes) but on a mobile device the image is removed.
Mobile CGI Driven Pages. This is where ShopSite takes your page and product databases, and recreates your pages when a customer comes to your website using their mobile device. These pages are created on the fly, so they only exist when a customer views your page, and they do take time to be 'built.'
|Responsive Design||CGI Driven Pages|
|Pricing (the biggie)||over $1000||Free in ShopSite (Mgr and Pro)|
|SEO Friendly||Great for SEO||Doesn't harm SEO|
|Buggy?||Can be. You often need to check ALL web pages.||Not really. Custom code could mess things up, but for the most part its not buggy.|
|Speed||Loads as fast as your regular site (same code).||Built on the fly. Slower, but negligible.|
|Set Up||Lots of work initially.||Minimal work initially.|
|Adaptability||Responds to different screen sizes, so will adapt as new devices come out.||Only responds to mobile devices (not tablets), and is a little more specific on width of devices.|
|End User Comments||No "view full HTML site" link.||Must switch to full HTML site for some features.|
Which is right for you?
Do you have a lot of mobile or tablet visitors?
You can check this in your Google Analytics account. If you have lots of mobile visitors, then I would highly recommend responsive design. If you don't have many yet, you can start with the CGI mobile pages and see if that has an impact on your mobile visitors. You may also be in an industry where mobile is not as important, and you may not want to put forth the investment for the type of return you would get.
How large is your website?
If you have a smaller site (less than 100 pages, including product more information pages), then you may want to lean towards responsive design. It isn't too time consuming to go through 100 pages or less to double check that they all look the way you want.
Things To Consider
Be ahead of the curve
It is always better to get your mobile setup in place BEFORE you need a mobile setup. This gives you time to trouble shoot without being inundated with mobile visitors.
What is the quick/mobile important information?
With both responsive design and CGI driven design, you typically want to remove some things from the page, or make them much less noticeable. Don't try to display everything that you have on your main site on a mobile device. Mobile customers are typically going to your site with a purpose. Make the main products, main contact links, or other focus information easy to navigate to (one click).
Have fun with mobile
I find mobile browsing and testing really enjoyable. It is fun to see your website on many different devices, with slightly different looks, and even some different focuses. Whenever you make a change, note that change in your Google Analytics (or other tracking software) so that you can see what improves your website, what your customers respond to, and what may not be worth putting as much time into.