I have been using Synchronize pro since 2002, and made it up to version 3.5 before my 2-year license period expired. It has been quite reliable and useful software, even if the interface is a bit lacking in the intuitiveness department.
However, a major headache in the past was the licensing of this application, particularly in the way that licensing terms changed several times. I am someone who pays for all my software and have a strict anti-piracy policy for a large lab that I manage. That said, Qdea's policy of reporting usage back to a home server and "ensuring license compliance" is completely obnoxious and un-called for. Why should the developer need to know whether I personally use it to sync one or three machines? For some reason they think it is their business that even after I pay them $100 for the software, that they should step in and say: "Here's how you can use our software, and here's how you can't use our software, even if it is for your own personal use." Given that I have a lot of different machines that I deal with at different times, this makes the software into (expensive) crippleware.
The developer seems to have a basic lack of understanding of the human psyche that leads to this policy. That same lack of understanding is what has led to many ill-fated music "rental" services where you pay for and download a song, only to have it expire after so many uses or when you download a new song. Why has the iTunes store been so successful? Because it gave people the sense that they _own_ the music they downloaded (even if it is not strictly true in a legal sense). People want to be able to do what they want with an item they pay for (just look at the latest announcement that downloads from EMI will be DRM free). The point is that Qdea does not give the user a sense of ownership if they are paying for the software. This only discourages legal users, not pirates (a sophisticated pirate could defeat the scheme).
I talked to the developer about this several years ago, and we actually had a rather heated discussion on the phone. He got very rude with me, basically telling me if I didn't like it not to buy it. Right, good advice.
I am writing this now for the following reason. Having moved over to an intel-based machine, I've been having some flakiness with the older version of Synchronize pro running under Rosetta, so I decided to look into an "upgrade". I optimistically thought maybe the developer would have figured out by now that he was loosing sales. I went to the developer's site, and saw that the draconian policy is still in place. He wants me to pay $49 to renew crippleware? Forget it. I would happily pay that price for software that does what Synchronize Pro does, without telling me how I can use it. I would have clicked "buy" right now, if that policy had changed (despite the developer's rude response to me previously). Fortunately, there are other programs I can spend my $49 on that are not crippleware.

Bottom line: great software technically, horrible from the perspective that you should be able to use software you "own" as you please.