I think it is much easier to keep a dynasty league together without money for two reasons. The first is that when someone is bad at this and they ditch a really crap roster, its easier to get someone else to take it over. And secondly, when the (nameless) super-active trade guy who also happens to know all the participants better than others makes a LOT of trades that might seem lopsided, the hurt feelings are attached to much lower stakes. I'd also be interested.