We integrate Magento shopping carts all the time with various POS , Accounting, Inventory Management / Fulfillment software.
The key to integrating Magento with any other types of systems is the API that Magento has.
It is a very good and robust api that allows you to retrieve, update, delete, create, etc. anything pertaining to orders, customers, products, etc.
Hikashop does not have an API like magento, so it is much more difficult to integrate other systems.
If Hikashop had an API system like Magento that would allow you to create API users, API keys, and API permissions to Create/Update/Retrieve/etc. Customers/Orders/Products/etc. , then the sky would be the limit in terms of integrating other systems like POS or accounting.
Nicholas, have you looked into what it would take to create an API system for Hikashop like Magento currently has?
We would be willing to contribute financially to this as I am sure several others would too, if there was a clear budget and development plan laid out that we could see.
We could even help with the programming side of things if you are able to organize it into a clear plan that we can all rally around.
We have a lot of higher-end clients that require integration with other systems and we have to use Magento for all of their sites instead of hikashop because of their need for an API system like magento has.
Anyways, that is my two cents on it all.