Beacon reviews is an interesting site. I personally think the Pulse and S1 are overkill unless you really think you will be doing a lot of multi-victim searches (which is not likely) but the Pulse is a nice, solid unit - bar the reported frozen switch issue. The S1, after being announced 2 years too early missed the boat a bit which is probably why there are not too many reviews. Here is some information from an Ortovox S1 user:
The Ortovox S1 has about 50 meters maximum range, a bit less than advertised. It is not an easy beacon to master. The user guide is not very clear (this seems to be a problem with Ortovox instructions which are not always well translated). The beacon is very precise as long as you don’t move too rapidly. You often have to stop to let it catch up. It is extremely accurate with distances and burial depths. It has trouble with more than 3 victims but there is a special mode for this where it will focus (at bit like the Tracker DTS) in a strip of 10 meters but you have train to use this. The beacon would be ideal for a group leader, guide etc who can put in some time to master it. The Pulse is easier to use.
Ortovox update the software on the S1 from time to time so some issues may have improved within the limits of processor power.
The Tracker DTS is a good dependable beacon, some comments say the range is not good but it seemed about the same as other digital beacons - that is about 35 meters in good conditions with a search band of perhaps 20 meters when I tested it. The Nic-Impex ARVA range are good basic digital transceivers.
Neither the Tracker DTS nor Nic-Impex have the advanced graphics of the Pulse or S1 but they are a lot cheaper and have reliable multi-victim search modes in the very unlikely event you need such functionality.