I've been trying Resolve12 lately, and doing one easy complete project on it, during their Beta3 and Beta4 release.
Still so much to learn, including the roundtrip between Sony Vegas and Resolve.
Perhaps anyone who has experience on this can share what to watch, Sony Vegas' feature that work / doesn't work (like Multicam / multiple takes, track envelopes, transitions, etc.)
I'm still on 11, but I've been using it with Vegas 12 and other user's Prem. sessions for the last couple years via the final cut XML interface.
I make cineform AVI proxys in Resolve of my BMCC footage. Edit in vegas and do all my sound synk/ work in there. Send the final cut XML back to resolve. I render out a final audio mix from Vegas.
It will synk the edit with crossfades and reverses. You will need to redo any reframing, I do all color work there and the final render out of resolve. The one weird thing is that in resolve you may get some incorrect clips due to time code 'overlaps'. It's just a matter of clicking on the triangle in the lower left corner of the clip and selecting the right clip. Resolve flags where you need to do this. I call it 'follow the bouncing triangle'.
I would stay away from any special stuff like multi cam. stick to straight cuts and grouping clips and you will be fine. Othe NLEs have had similar issues with stuff not making it across. Resolve has some limitations and what it can take in. Make sure you have a locked edit. there is currently no way to update an existing edit in resolve when you round trip. I'll be estatic when that happens....
the resolve / vegas pairing works really nice. They compliment each other's strengths and weaknesses very well.