Thanks for the info about jBridge, I didn't know about it. And thanks for the link to Kamioooka, too. I have a whole queue of soft synths already installed and waiting to be explored but I don't mind adding one more. :)
By the way, I've spent a bit more time mucking about in Reaktor Blocks and it turns out the basic free version is somewhat limited. It has your filter, lfo, envelope and a basic sequencer but no effects. So kinda like Kamioooka, actually. I still like the idea of using it in my DAW as sound source though.