One of the hardest obstacles for a small software company to overcome is the very fact that they're a small company. The argument that the company may go out of business can cloud decision makers thinking from quality and capability to worrying about how to find support for software or how to replace it if the worst happens. What decision makers fail to realize is the very same reasons they worry about small companies goes for large companies as well! You ask how? Well its not uncommon for large software businesses to simply abandon a product because it wasn't aligned with their business or they couldn't find a large enough market for the product or other technology appears to be the better solution. Software such as libraries like Sliverlight and high level APIs that used Directx, or SVG viewers, etc are just abandoned where all the development done by companies using those libraries or software products are left to find other solutions costing them millions of dollars in new development costs and wasting their past development efforts!
Surprisingly many small companies have adopted solutions to dealing with going out of business and that solution is software escrow. Many small companies guarantee their latest source code is housed in escrow where if the business should terminate their clients have access to the source code! These escrow agreements not only allow a business to continue maintenance but can allow their clients to develop the software as they please. Imagine the savings in development or replacement costs using this strategy. You'll never get that from an a large company if they abandon a software product!
Not only is a small software company a good business decision because of the accessibility of its source code but small software companies are more adept to customizing their software to a client's needs and the support is very timely. For comparison a large company doesn't necessarily fix a bug or create a new feature until a substantial number of their clients demand a fix or feature. This can take months and sometimes years before a fix or feature ends up in their product. For small companies any bug or new feature, even if they are specific to one client, have a very high priority and prompt attention to fix or create the feature. This means seeing corrections in days if not weeks in comparison to months or years.
So when evaluating a small company ask if their source code is in escrow and find out what their support service is like. Small isn't inferior to big and big doesn't guarantee indefinite or timely support.