The way I see it.. and this is purely my own opinion from someone who owns both the competitor's product as well as the RB. The ability to design you're own apps adds to the value of the product rather than takes it away. I do a little programming in VB and i've been using the competitor's product due to the lack of 5 minute delay in data for my software.
Google has the right idea by open sourcing a lot of their products so third party apps can enhance the product offering. As an example, people use their API's all the time to develop mashups and software, but it doesn't turn people away from using their software. If anything, it adds to their value and people use it more. The same can be said about Firefox and the extensions that are built.
I personally don't think turning off the 5 minute delay would harm the live network simply because the network is already established and adds even more value to the device.
It's all about adding value to the device. As mentioned earlier, this is a niche market and in my opinion the thing that differentiates is the ability to customize what you do with the live data. Some great ideas can make the product stand out and improve the software if it was developed by the people rather than the internal developers at Airnav, or the competitor.
Personally, if I was airnav, I'd be changing the business model slightly, and doing things like creating an API for people to build their own applications with the live data, and removing the 5 minute delay.
Airnav can still have their live network as I don't think it will harm their income model. Look at the competitor. People have had the live data patch for years, and there still isn't a network anywhere near as big as Airnav's live network.
Essentially, the live network that already exists is big enough to hold it's own as a value added service. Add on top of that, the ability to build further enhancements by people that use the product, and I think it would be a huge selling point.
Right now, I must admit, the biggest selling point of the competitor's product to me is the lack of 5 minute delay whether by native, or by patch. We all know that everyone is asking for different features. A lot of the features are already in the other product. What better way of gaining market share than to match the other product's features, and allow an API for a mass of other applications to be built.
I have both devices because both have features I like. If I was Airnav, i'd be focusing on matching every single feature, and then some, that way people won't give the competitor a second look.
Because this is a niche product, I believe the more ways to customize the data, the better.
Just my own opinions though. I really hope Airnav in their internal discussions decide to drop the 5 minute delay at the very least. Imho it will really add value to the product.