It's getting harder, with the size of the engine now... I had to have a fortnight away from it because it was just getting so cumbersome implementing things... But, I defo think I have the "brunt" of it in, and, apart the geometry manipulation stuff, I'll be moving on to brushes etc etc
Then, I'll have a bit of a beta release (Set up it's own forum and such), so if you want to be added, I'll give you a shout when I'm at that point... At the minute, there probably is a bit of dev bias going off, so ideally, to tune it, it needs to be tested by others too... Others break things, which is nice! :P hehehe