comparison between gh to revit connections

I am trying to understand the differences between all these interesting projects.

It seems there are at least 6 major works being developed to bridge the gap between grasshopper and revit:

Lyrebird,

GRevit,

Chameleon,

Hummingbird,

VisualARQ,

and Geometry Gym.

So far the major differences that I can see are:

wether they work with Revit 2014, or 2015...

how they transfer data, via csv/excel or via IFC or via some proprietary back channel. 

and if they are open source or trial.

Do any of them update live or are they all requiring a push from one program to the other.  also do they in general go from GH to revit or are any sending info both ways?

Do any of them link through Dynamo?

Does anyone have experience with these tools that can offer more observations on the differences or similarities, strengths and weaknesses. Anyone care to say which is their favourite?

Thanks for the help! Ethan

update...

WOW I just saw these links to this gh Vasari talk and I will watch those now and add my notes to this thread...