Hey psw, dont be dishartened about the fact your sustainer project isnt going to well at the moment. All designers who are doing something new go through the stage of realising the possibility that they may be out of their depth. The key to it all is research research research. Oh, and also a lot of determination. To me, if you have achieved infinate sustain, no matter how big, your a lot of the way there already. Your task is just to compress it all.
I have a little quote for you that should help keep you motivated and realise you can do this, even though you probably have this correct attitude already. It is from the guitar builder who built the custom guitars for Matt Bellamy from Muse, I dont know if you have heared of them, but they did a tour in the states recently, not sure if they have ever been to Austrailia. But anyway, this is what he said about one of his guitars he made, and I think it can apply to most if not all things:
"It’s funny how something that starts out being a good project, goes through this potential disaster stage and comes round to being a massive success."