No. Quite the contrary.
The control panel of ezimerchant (web based) is very fast and has lots of features which make it quicker and easier to use than version 4. For example, you no longer need to resize images - all you do is upload your original sized image and ezimerchant will automatically take care of resizing for you. The best part is though that because we store the full size image you can change your mind regarding the size of thumbnails, large images, cart thumbnails, search thumbnails or wherever / however else you want to display product images just by making a change to the template.
There are a lot of one click functions, especially in the catalogue management and orders screens. It is possible to batch process orders and batch edit products. ezimerchant is fast and will continue to evolve to get better and better.
Anyone with a moderate to large catalogue will benefit from the fact that there is no more site generation.
The stock control functionality eliminates the need to manually update products when they become unavailable.
We specialise in building secure web applications. Your version 4 based website has benefited from that security for many years through the security of the GTS. We have processed over 5 million transactions representing hundreds of millions of dollars (that's right, over half a billion dollars). ezimerchant (web based) adds to that security by taking your site administration online. You will no longer be responsible for securing sensitive customer data on your computer.