This is always a problematic method when it comes to concurrency, locking, and PowerShell. Honestly, a much more scalable, robust, and also fully supported method is the SovLabs DNS module which doesn't require any vRO coding or EBS subscriptions on your part, and you can use different connection methods to your MSDNS server. I've seen zero problems running this in high scale or high concurrency deployments.
I was afraid someone would say that...
We attempted to engage sovlabs on pricing, and cant seem to get a straight answer without them fully engaging.
Regarding the DNS Record workflow from PSCoE on the solution exchange.
There is the ability to add multiple powershell hosts in the configurations / attributes for the workflow (we added three).
The issue here is the first host in the list is the only one that is called from the workflow, and the ability to round robin between them combined with some delay timers might resolve the issue.
Also, we have been considering moving DNS to the infoblox appliance, as it currently does our IPAM for the environment.
Motivation to move in that direction I suppose, although the in service people may have some strong objections to that.
Thanks for the feedback.
You might want to speak with them regarding pricing anyhow. It's usually never as simple as asking a company, "how much for this thing?" and they give you the answer. It might be worth your time to check it out. I've had mixed luck with just about anything else when you start getting into concurrency issues, and PowerShell hosts are the worst about that (not just with DNS but with module invocation as well). They also have Infoblox integration for both DNS and IPAM, and I've used that fairly extensively again without any observed issues with as many as 500 deployments a day.