I am sure Keith helped you quite a bit. Unlike me, his business is selling and installing the equipment in the various Mercedes models, and he is familiar with the intricacies of each.
With regard to the telephone modules: The original StarTac PSE, the TimePort PSE, and the Autosense PSE will work with the V60 (5856) puck AS LONG AS they have the "Blue Label" as described in the writeup. To the best of my understanding, the "blue label" indicates that a firmware update was applied that allows them to work with the puck, and not be limited to plug-in phones. I suspect, without confirmation, that the update allowed them to accept the "handshake" from the puck that an MB-branded plug-in phone would have provided when connecting to the system (if the plug-ins were not MB branded, the phone system would turn itself off). The Bluetooth puck allowed non-MB branded Bluetooth phones to work with the system.
The difference a user will see among those three PSEs is that the StarTac would not display caller ID for an incoming call. The others do. However, I am not sure about whether all three would work with MB head units for which they were not designed - i.e., I am not certain that a TimePort PSE would always work with a car designed for an Autosense PSE. In my '00 I was able successfully replace the original StarTac PSE with a TimePort (to get caller ID), and it worked with the '00 COMAND unit - but that is hardly enough to draw a general conclusion.
As stock of the older PSEs were exhausted, MB came out with the "Universal PSE." It was designed to work in all the cars that would originally have had a StarTac, TimePort or Autosense PSE, and it was produced at a time when many states were requiring handsfree devices for cell phone use, and owners would wish to install Bluetooth in cars that never had a phone system.
To answer your question - a good one - the PSE used (except the StarTac PSE's inability to display caller ID) is not the limiting factor in compatibility with newer phones. The PSE essentially performs the integration and enables the control functions between the head unit and the steering wheel controls. With plug-in phones, it also connects to the car's external antenna. The limiting factor is the Bluetooth firmware and protocol stack loaded into the puck itself (information MB does not provide). That discussion can get a bit technical - one of the simpler, but relatively thorough discussions of it is at https://en.wikipedia.org/wiki/Bluetooth
. Unfortunately, cell service providers frequently alter elements of the protocol stack to serve their own interests (e.g., Verizon is notorious for limiting or altering the stacks to force users to its "business partners" for certain services). When service providers do this, then the "Bluetooth standard" becomes pretty much non-standard. Fortunately, the basic Bluetooth core is supposed to be backward compatible, meaning that a newer phone should perform its basic functions with an older version of Bluetooth loaded into the car's equipment. But it does not ensure that you will get every function with every phone. That is why I say, test any phone you intend to buy with your car's system before you buy. Most full-service stores will have one that a representative can take to your car and test it for you.
I will say that iPhone 4 and 5 owners have reported success with the V60 puck. That's pretty recent technology - but for compatibility with the myriad other brands, you'll have to search the web, or try them yourself.
BTW - the discussion in the preceding paragraph applies to the pucks for MHI systems as well. The firmware suite in the 5878 and 6131 pucks is newer and is compatible with more phones than either the earlier MHI puck (5839) or the V60 puck discussed. Though their appearance is different, as far as I know the firmware of the 5878 and 6131 MHI pucks is the same. However, any system that uses a PSE instead of an MHI controller is limited to the V60 puck. In addition, the CP-211 system installed in certain models and only in certain years uses a "puck with tail" that has the same capabilities as the V60 puck discussed above.
Realizing also that Bluetooth overcomes the need for any kind of cradle, MB came out with the Cradle Eliminator Cable to connect the V60 puck to the system, instead of requiring owners to also buy a cradle. That was a good move, because the V60 puck dimensions fit the newer V60S cradles; it did not fit the older V60 cradles well, which caused some connection problems. The V60S phone was bigger than the older V60 phones because they had additional electronics in order to be E911 compliant (the function that allows phone locations to be triangulated from cell towers).
I'll repeat a note here: The V60 puck together with a cradle eliminator cable may resemble the "puck with tail" used with the CP-211, but the connectors to the console are entirely different.
All that is history, and it is scattered throughout this lengthy thread, making it hard to put together. It won't help you install the equipment in your car, but perhaps it will help to understand some of the complexities.
One thing (mentioned in the first post, but worth repeating) - if you are installing an MB phone system in a car that never had one, version coding is required so that you get full functionality of the system. If you are replacing a system in a car that had a phone system, version coding was done at the time of the original installation, and is not necessary.