My understanding (from End Tuning here in UK who has been doing these for a very long time) is that ECU in the M52B28 is old and not very clever like high performance modern stuff so dyno tuning is not that beneficial for them.
Active Autowerke say:
An increased RPM limit (for manual applications) is another great feature the Active Autowerke E36 328i software provides owners. With this raised rev limit, you have the ability to enjoy more usable power which had previously been restricted under the stock parameters.
The raised limit is known to cause issues with the oil pump nut falling off- the ‘eBay’ seller I used was keen to point this out. He also advised against doing a ‘pop bang’ map. eBay is just the medium you buy through.
These guys don’t even warn against the raised limit issues which does make me wonder.
As far as I know the oil pump nut issue is an issue with M54 3.0 because of the harmonic vibration set up by the bore/stroke ratio. 2.8 is square meaning bore and stroke are the same and I believe do not suffer from this vibration at higher revs.
In terms of the DME being dumb... Well it can control fuel and timing perfectly which is pretty much what you need for a remap in order to push the spark advance for your fuel and environmential conditions and bring the AFR down from 14.7 to something that creates more power at wot when its on open loop.
What else does it need to be able to do on an engine that does not have infinitely variable vanos.
In terms of the increased rev limit on an M52tu with the stock intake manifold it is not a benefit apart from making people feel good. Stock it falls off a cliff from a breathing point of view way before that. With an M54 intake manifold and intake cam it pulls all the way and would go boom without a rev limiter.
If I am incorrect about the DME being tuneable or the oil pump nut I would love to be corrected so I learn something.
Edit
I would NEVER run a tune without being able to verify actual AFR and knock with my air and my fuel. Engines that melt pistons are hard to fix. Canned tunes are a really bad idea without you being to verify that they are safe.