The Pieps DSP Tour was released in 10/2011 and discontinued in 11/2013. The Pieps Tour was replaced by the Pieps DSP Sport in October 2013.
Summary: The now-discontinued Pieps Tour is the nearly-identical twin to the popular Pieps DSP, but it has one button (versus the three on the DSP). The result is an easier to use avalanche transceiver with a lower price tag.
The Pieps Tour was replaced by the Pieps DSP Sport in October 2013 after Pieps was acquired by Black Diamond Equipment. Black Diamond also lowered the price by $75.
Ease of use: The single-button Tour is as easy to use as it gets. A clearly labeled switch can be in one of three positions: Off, Send, and Search. The one-button interface allows you to "Mark" (i.e., ignore) a transmitter during a multiple burial search. (Read about a potential problem with the switch.)
The only thing confusing about this beacon is its name. Pieps refers to it as the "DSP Tour" which is easy to confuse with the Pieps DSP (and now the Pieps DSP Sport and Pieps DSP Pro). And looking at the transceiver, you'll need a magnifying glass to read the word "Tour" just below the "Pieps" label.
Removed Features: The lack of the DSP's Scan and Enter buttons results in the loss of three relatively minor features. The Tour doesn't have the DSP's ability to scan for multiple beacons at various distances, it doesn't test the frequency of other transceivers, and it doesn't support searching for the Pieps TX600 dog transmitter. Those features might be important for a few folks, but as with the Ortovox 3+, the Trackers, and the Element, the trend toward simplicity is fantastic.
Remaining Features: Other than the removal of the three features and the lower price, the Tour is identical to the DSP. Read the full review of the DSP for details.