Hello Melgebal,
I think it would be helpful for all potential consumers of your outlined practices to understand the context and situation in which you would recommend the above, and specifically what caveats you are introducing by doing such. I would go so far as to mention there are some practices that have worked for you in your deployment, but should be taken with a grain of salt for other deployments. I mention this with the following in mind
1. There is a Cisco Best Practices Guide for ACI which was vetted by both TAC and TMEs which contains recommendations which go against some of what you mention.
a. One example is that if you are using an L2 only BD, it is strongly recommended to NOT enable unicast routing, as this has potential to cause problems related to IP learning and routing occurring through the fabric if not properly accounted for during design.
b. Another is related to "Limit learning to IP subnets", specifically why it became the default setting for new BDs. In general, if you are defining a subnet in ACI, you are having that IP act as a gateway for that subnet. The implication of learning IPs outside of that subnet is that either some external device is sending traffic to an unexpected VLAN, or a gateway configuration is missing on ACI that should be there to account for this subnet. I have not yet personally seen any scenarios where a user of ACI is purposefully learning IPs outside of the configured subnets.
c. Endpoint Dataplane Learning is on by default, and is an option with a very specific purpose (PBR for L4-l7).
Again, some context around why those settings work for you (and perhaps some insight into what your fabric was doing, maybe L2 only?) and what value you got from them would allow others to judge them truly for their setups.
-Gabriel
