- Does your favorite body have a database function one can build up in the body that stamps the lens name into the Exif and sets the IBIS right (if it has IBIS)?
No idea / I don't use that.
- Does your favorite body support adapted lenses in any other good way?
Ex.tele feature provides that extra tiny bit of zoom.
Not sure what that is. Are you talking about so-called "digital zoom?"
No, it is crop-sensor zoom. Just as much as the 4/3 sensor appears to give a 2x zoom effect compared to FF sensor image then a crop sensor can give the appearance of a great image by simply using a smaller part of the sensor (less pixels) but the 20mp sensor does allow some spare pixels that can allow this to happen in a reasonable manner.
This is actually a fairly common practice. Bridge cameras with tiny sensors could use the crop sensor technique to claim impossibly high technical levels of zoom by further cropping an already tiny sensor. Ricoh did the same starting with its GRD but was more honest about the apparent zoom by clearly advising that this zoom was accompanied by rapidly deceasing numbers of pixels used.
FF camera usually use the same technique of auto crop sensor for aps-c lenses when attached. Many are quite amazed at the fact that aps-c lenses can be used with no apparent reduction in quality of the image.
For example the L-Mount FF S1 camera body normally uses the full 20mp sensor with FF capable lenses but when a functioning AF lens with aps-c image circle is mounted it only uses 10mp of that sensor and the lens appears to be working normally as an aps-c lens with the quality of its aps-c image circle making an excellent 10mp image.
No - crop sensor 'Ex.Tele" is not the same as digital zoom.
IBIS prompt asks to confirm lens mm setting (since it cannot speak to the vintage glass in any way)
No sense trying to convert an P user to O (or vice-versa), but having IBIS interrupt me to ask questions would drive me nuts.
Yes it can be slightly annoying being nagged at start up to check that if you have now changed your MF lens setting for IBIS. But this seems to be what 'all' (other) camera manufacturers seem to do. It is cancelled by a soft press of the shutter button which does not seem to be a great burden. On the other hand how many Olympus users of MF lenses forget to change the IBIS setting when they swap lenses? Then there is the issue that on my E-M1 at least there is no way to check what your current IBIS setting is other than to commence the button and wheel spinning dance to set about changing it. Did I change it or didn't I? In practice a lot more complex than the Panasonic 'nagging'.
Many (most?) Olympus/OMDS bodies have a "registry" where you can enter an EXIF name, focal length, and maximum focal ratio. Then, when you use that lens, all you have to do is select it in the registry.
Yes the registry is a good idea but is selecting a lens from your registry any more simple than a simple soft press to confirm or a left arrow and a once only easy access dial spin to change the setting?
It's limited to ten items, which is a pain if you use focal reducers and tele-extenders, but it's better than having the camera ask you, "What's the focal length?" each time you change manual lenses.
It is worse than that the nag screen pops up every time you switch the camera on the with a MF lens attached. But soft press and it goes away and if you do happen to have changed your lens it is a handy reminder that your IBIS needs changing and it is so easy to do so.
It is real nice to have your non-electronic lenses identified in EXIF data! Does Panny do this?
No. But I have several hundred MF lenses and counting - 10 slots are not nearly enough

Managing a ten-slot limit with a larger-pool number of lenses in use is going to be an exercise in frustration that I would find much more of a nuisance than not remembering which lens I had used.
I program the front two buttons on the E-M1.2 and OM-1 to 1) select from the list of ten manual lenses, and 2) focus peaking. Makes manual lenses so easy to use!
I have focus peaking on 100% and in fact the later Panasonic models allow focus peaking to be shown even with oem M4/3 lenses. I like to see confirmation visually of just what extended parts of my image appear to be in focus even when using that AF system.
I don't need to fiddle with my focus peaking setting but I could assign it to a button if I really needed to do this.
Having it fro AF also helps to catch the occasional mis-focus on the wrong subject matter by our AF system.
So M4/3 is good and we at least have great variety of choice in our camera body styles unlike some other brands we could mention.
