Actually, this is incorrect. Yes, 802.11r can improve roaming transition speeds, but it isn't magic, and sometimes it can actually be detrimental to roaming performance because some client devices just don't work well with this standard.
Your phrasing here suggests that roaming "kind of' works without 802.11r. In actuality, roaming can work really well without the addition of 802.11r. When a client "holds on" to a specific AP, that is actually a sign that the radios have not been properly optimized in your environment. Specifically, the use of non-overlapping channels for neighboring APs, power level adjustments (almost always reduced power), and physical placement (to the extent possible) of the APs will help improve roaming performance by encouraging the client devices to make good roaming choices by means of the signal quality factors after everything is optimized.
This is ideally true, but not always in practice. First, the radio optimization I mentioned above must be done as a foundational step. Then, if there is a need for faster/smoother handoffs, 802.11r can be added on top of a well tuned wifi network. Keep in mind, though, that not all devices play well with 802.11r (especially IoT devices and things with inexpensive/low-end radio devices), and this can actually cause more problems that it solves in some situations. However, assuming that you don't have any deleterious effects, 802.11r will only really add value if the radio tuning has been performed because the system as a whole will still be based on logic that triggers based on thresholds of signal quality.
I do not recommend this unless there is a demonstrated need for it (and only after radio tuning is complete).
Again, band steering may only lead to issues in many situations. Let the client devices select the AP and the band based on their own internal logic -- this tends to work much better than AP settings that include fast roaming and band steering.
DAWN and other methods of handling large deployments is overkill for most homes, even large ones. I generally see it as filling a more enterprise need (businesses, schools, etc.) where you're dealing with many dozens of APs and hundreds or thousands of client devices. It's also fairly complex to setup and deploy, so the steep learning curve would likely only result in performance issues while the user learns how to use the tool.
Bottom line: keep it simple.
- As others have stated, if you are able to use ethernet backhaul, this is preferred and means you do not need or want mesh.
- Setup your APs in locations where you can ensure good coverage across your space.
- optimize the power levels and channels to minimize the zone of overlap so that client devices make smart roaming decisions.
I really like the way this video walks though the optimization process... it specifically mentions Unifi, but applies to any wifi system as long as the appropriate settings are exposed to the user (yes, OpenWrt has them exposed and available).