To share my own experience:
I ran Certify v3 for some time and it always performed flawlessly. This is all in use in a home lab/setup environment, by the way.
When I got wind of the v4 alpha testing with DNS support for wildcard certificates I jumped at the chance to get on board.
The first thing I had to do was move my DNS to one of the supported providers as the one I’ve used for years, although very reliable has no API system that I’m aware of and certainly not ever likely to be supported anyway.
I picked Azure simply because I have Office 365 accounts etc and it kind of just made sense as things like extra email domains DNS can be configured automatically in future.
I have to say that although configuring the DNS settings for a domain are trivial - anyone who’s ever done it in any kind of web console will find their way around it (although I stumbled at first because I failed to notice the fqdn was pre-populated so I ended up with resouce.domain.com.domain.com but that was user error.
Getting it configured properly for Certify though was a nightmare and I feel that Microsoft have made it overly complicated to the extreme.
I did, ultimately get it working and have shared the steps with Chris to hopefully help anyone else to get there more easily and it’s working an absolute treat.
I can’t thank Chris enough for his effort and his willingness to respond and help - he pointed me at some valuable resources that although slightly wrong in places, did ensure I could piece the missing parts together.
My experience is therefore a bit mixed - from Chris it’s brilliant but from Microsoft it was just not good.
Anyone needing automation for their wildcard certs in IIS really have no need to look anywhere else in my humble opinion.