Several years ago I had someone approach me asking me the same question.
I told him that there was no reason not to. The only issue was if you were planning the connect their modules with another group you would have to build a simple adaptor module with Unitrack on one end and standard (or matching) track on the other end, or use their snap track adaptor sections.
If I recall, he was planning to use Kato's Expansion track for the joints?
Using a larger radii on the balloons is never a bad thing.