I have not tried your software myself as I am comfortable with my current way of tracking my collection and did not relish the thought of the time involved to convert all my info over to a new system. And before I started my business I was an accounting manager, so I doubt I need too much help in that regard either. But just a couple of thoughts of the top of my head if you are going to tailor this to collectors.
Make sure your software has the ability to track all the costs. Beyond the original purchase cost a collector may incur additional costs during the time he/she owns a coin. Costs like sending to CAC, cost to reholder a coin, costs to have professional photos taken (including all shipping and handling costs). Many collectors never record all these ancillary costs and do not really know the true full cost of a coin in their collection. Perhaps a place to record insurance costs, bank vault costs, costs to attend shows or auctions could also be a useful tool for those that want to track the full nut costs of coin ownership. And of course disposal costs should be included too. My specialty was cost accounting so my mind just works that way.
I'm not a dealer so I will not attempt to provide any feedback in that regard.