I think that instead of having each connection factory be separate with no-tx, local-tx and xa-tx - we should just have a <transaction-support> which can override the RA specified one.
Then in our deployer will just ignore attributes/elements which doesn't make sense for the connection manager in question.
I see this as a largely usability / documentation issue -- the format should be as simple as possible, so focus on setting the JNDI name for a single connection factory first, and we will work from there.