A quick buying tip specific to what I like to call vapor features or vapor functions. Over the years I have come across companies that advertise functions or features within their point of sale programs that don't yet exist (thus the term "vapor").
The warning here is that your demo of a point of sale system should include real world testing of any specific features or functions that you require of the system. If the vendor tells you that something is "in development" then that means that a particular feature or function could be months away from being released.
A good example would be gift cards. While you can write out paper gift certificates, life is much easier if your point of sale system tracks the gift cards for you. If the point of sale company tells you that the gift card feature is not yet available for the point of sale program but is "in development" then you may still be writing out paper gift certificates for awhile (and yet have paid for a new point of sale system that was supposed to reduce manual processes and make your life easier).
The point being is that if you need the point of sale program to include a specific feature or perform a specific function, make sure that the program can do this now. Otherwise you may be waiting some time for an update to be released.
As a side note, I question the ethics of any company that advertises a feature or function that is not yet available.