Fair point on the lack of internet connectivity. Web-POS is not ideal for stores without broadband Internet (although this must also make it tough to process credit cards real time as most processors now require broadband).

This does bring up another point on web-based POS vendors. You should check into how web-based POS applications work with network outages. Most web-based POS apps do not work when the internet goes down. There are a couple (VendHQ and MicroBiz) that enable retailers to ring up transactions when the Internet is down by maintaining a small applet on the computer that can continue to process transactions w/o an internet connection. These apps store the transaction data locally during outages, and when the Internet comes back online, the data is automatically synched with the "cloud".

Again, cloud-based apps will continue to grow in popularity given all their advantages (instant updates, continual data back-up,ability to access the app anywhere, anywhere and on any type of device) but some retailers may have issues (such as lack of internet) that may limit their ability to realize these advantages.