Before purchasing a Commercial License, one thing I would like is the ability to compile the native code for debugging purposes. Upon a crash, I really want to be able to trace into the sources and provide accurate reports/fixes back to NeoAxis. I also think this would be good for fixes/patches/improvements being sent back to NeoAxis.
I can't really see a downside to the Commercial License coming with "read only" source code, defined in the EULA.
The $10,000 Source License would retain the right to distribute derivative binaries. Which is fitting for the expense.
I think this could help:
1) Get more people working with the source code and providing accurate reports/fixes/patches
2) Provide incentive to buy the Commercial License as a fair number of sales are probably lost to people not trusting something they can't recompile. It also further differentiates the Commercial License from the Indie License
3) Keeps the Source License valuable (it is absolutely worth $10k to be able to make a derivative work and redistribute it!). The Source License is most likely intended for (advanced) teams enhancing the C++ engine for simulations and shipped products. That makes sense and doesn't have to exclude providing Commercial Licensees with the means to debug their games, help contribute fixes/patches back to NeoAxis, and in the end grant them the possibility to understand/enhance the C++ code which means more potential Source Licenses, more finished games which are the best marketing for a game engine, and perhaps more powerful addons, which all add value... and keeps NeoAxis in control, steering, and generating revenue from the engine.
I hope this makes sense, NeoAxis really rocks and deserves great success!
PS: I think a number of Commercial Licensees would probably be willing to pay a yearly fee for read only repository access as well. This would be a yearly renewal/subscription to help keep NeoAxis with some additional cashflow. $395 Commercial License + $195 for 12 months of repository access sounds good from this vantage point... and over the course of 2 years, instead of a $95 Indie License or a $395 Commercial License, NeoAxis sees nearly $800 and makes the Commercial License that much more attractive to purchase.