Mdaemon helped us a lot to benchmark our pricing. They give a clear pricing calculator and they are not a full security network node like ours. There are several differences but you already know them.
Mdaemon is old player but not as big a brand as Proofpoint and you don't read much about them in the news anyway. We get a feel that it is better to run a full network node like ours to remove dependency on certain plugins or OS.
The company is based in London and makes it quite easy to transact on the web like us. That is the philosophy where we agree a lot. No corporate messaging, they make things really easy and straight forward for you to transact try and do business.
End of the day what matters is your comfort with a given vendor. We are deeply technical, passionate about what we do and highly focused. Most of the competing players are well funded with multiple 100s or 1000s of employees and personnel, we are a very close knit group.
We are also very open source centric with focus on latest trends in open source world. Usually something new in open source that is licensed for commercial use finds its way into us.