As was mentioned, there's no doubt the G4/G5 outperform the SDS100/200 (as they should), particularly in terms of reception range (from what I've read). It's a matter of your requirements since the G4/G5 lack some of the functionality of a true scanner - kind of an apple-to-oranges situation. As much as I would have liked to buy a Unication, they simply don't meet my requirements for versatility, and I did not relish the idea of starting from scratch learning a new programming system. Because they share the same Sentinel software, making the move from a 436/536 to an SDS is very simple because you can essentially just clone one to the other.