DSXchange

Both formats contain exactly the same information. DSX is the more compact format, as it does not contain XML tags. Therefore I prefer DSX, as it creates a smaller file to store/email.

Be aware that xml is not faster when it comes to importing it as it must first be converted to dsx format and then imported. And that's not a speedy conversion.

I don't even believe it's faster during export, but have no evidence to support that belief.

I don't believe so either and also lack any empirical evidence to back that assertion up... it's all anecdotal.