Claus,
The hard thing about answering your question is that hardly anyone has first hand experience at all three. BTW, What grinder are you using?
As a Volante owner, I've been quite happy with my machine especially after installing Eric's adapter. Eric's adapter though has shown me how variable the heat output can be if I'm slightly off on my timing. Hx flushing in a plumbed in unit is a breeze and even more so when your drip pan is plumbed, tho I still use a cup for initial flush so I can rinse the PF after pulls and a bowl for wiggle rinsing to keep the drain lines cleaner. STILL, I got envious when visiting another members house and saw his Vibiemme double boiler in action. In a word effortless, another word quiet - more than the Volante. Not that this would decide MY purchase but the Volante has some ratings described by one vendor as:
And, to boot, this machine has an ETL rating for NSF 4 and UL 197 - the highest electrical and safety standards which allows it to be used inside restaurants and cafes. In fact, most local health departments not only request it, but require NSF approval. ETL Approval assures you the factory and machine production is inspected every three months for providing high quality and high safety standards.
How easy is it for you to get parts and service on any of these machines, should be a consideration. Sooner or later something will go wrong "what can go wrong will go wrong". Mine has already been in the shop. Brewtus has a big following and you've probably found a ton of web information on it. It is up to you to know how precise your taste buds will be to incremental changes in the temperature of the pull. I'm not sure I have the "right stuff" BUT I would like to have more accuracy hitting that method that gets me that sweet shot I love from the beans I love. For me its a combo of my method and I believe my temp control and a PID double boiler would remove one more variable. If you haven't already, do a search off my name and you'll find a pictorial thread I posted on the Volante and other hopefully helpful remarks. Mike McKoffee is also an excellent, highly knowledgeable source.
Again, what grinder are you using? It will make a BIG difference with all of these machines.
E