Some thoughts to consider:
I have several older Mercury SRS and other PBoxes. I love them. They are excellent units.
However, because the SR2 is limited to only two serial receivers, I recently bought another Mercury SRS for a spare versus ordering & waiting for the Mercury SR2. Given all the wiring with electric retracts, electric brakes, nav lights, etc. and all the carbon fiber they add to composite aircraft, I am a firm believer of having at least three serial receivers, especially in the smaller composite airframes. Also, it is hard to get all three possible antenna orientations covered with only two remotes. Lastly, with larger planes, the farther away we tend to fly them. There are lots of variables to consider when downsizing receiver capability that you know works!
I do like that the fact that the SR2 is smaller than the SRS and the high voltage is upped a bit too. But I prefer the built-in gyro of the SRS. Having to order a separate gyro opens the door to more supply chain delays for a complete setup (e.g. SR2s available but the gyros not available, etc.) Anyone suffered through a supply chain issue lately? Also, with the prices between the SRS and the SR2 with the optional gyro relatively the same, it hardly makes sense to have a separate gyro. For example, in spite of the smaller SR2 unit you now need more space to mount the separate gyro. But maybe there is some other advantage that I am NOT seeing here? Maybe some folks who would buy a SR2 would not want a gyro? To me it looks like PBox sacrificed the internal gyro to save some space which created the need for more deck space. But maybe it is a design or profit issue (e.g. one gyro fits all, etc.)
For me the jury is still out on the SR2. As these units start showing up at our field, time will tell if 2 vs. 3 Rxers makes a difference. In the meantime, my Grandpa taught me to never buy a first run production model anyway.
But coming from PBox, I am sure the hardware is great. However, my experience with their flawed terminal program necessary to update PBox software was doable but rather frustrating to say the least!