I bet the market conditions that led to this are broader than just GPU computing. I think it would more generally apply to any middleware business. But it is certainly more palatable for people in scientific computing and HPC to use something free and later pay for support and services and addons. Once people start really relying on the free thing, that reliance can be monetized. In this sense, it is more "scalable" to have an open source product which is readily adoptable by early users than to attempt to sell a product to buyers that have not yet started to rely upon it and have a good distance to go before reliance sets in. This is not SaaS and never will be, haha.
Allocation of future resources is something that we have considered a lot. I wrote before about opportunity costs associated with an open source business model: http://notonlyluck.com/2014/08/13/opportunity-costs-required...
We just open sourced today, but our plan is to treat the open source product the same as we have always treated it even when it was proprietary.
Great questions! Hit me up on Twitter @melonakos. Would be good to connect more with you, especially if you are going to SC'14 next week.