These platforms represent less than 5% of web applications built today. Firms building solutions on these platforms are most likely smaller and very specialized. A warning when considering minor platforms: the market leading platforms are leading for a reason - they represent the most vetted, long-lasting investments for the client. That said, "new and upcoming" platforms can be a fit as long as the software consultants are very familiar with them and are not using your project as a chance to "learn something cool".