One downside we see with Enhance and one reason we're not rolling out is hostnames for services.
For example the mail settings configuration should really give a hostname such as mail.domain.com and this then actively points to the server where the mail is pointed. This means if the mail process needs to move which may involve an IP change, the impact to the customer will be limited.
With them using a hard-set value to the server hostname, they'd have to reconfigure one or many devices if the server had to be relocated.
The same applies to MySQL, it would be good if hostnames (instead of IPs) were shown specific to the MySQL instance mapping, so if this is moved, as they use hostnames, there will be limited impact and users. This of course would need to be a hostname specific to the instance and not the server they are located.
At the moment, if the location of any service instance is moved, the email would break for user collection as would MySQL.
In addition to MySQL hostnames, it would be good if some services were able to have multiple interfaces (ie WAN/LAN) so that for MySQL traffic by default uses local traffic interfaces and the WAN access to MySQL is limited to only set IPs in the users CP.
I feel this is an area which has been implemented fairly poorly and it is so rigid it goes against the principles listed on your main site about being able to move things around easily; i'd argue having users reconfigure their devices or website software, not in keeping with that.