Using DTM as your campaign targeting layer

DTM has a whole load of targeting capability which includes being able to target Mboxes. Put another way, DTM can replace your Adobe Target campaign level targeting. So why bother?
Adding targeting at the Mbox level through DTM will reduce your Mbox server calls/costs. In the past if we wanted to run a homepage test for Mac OS visitors we'd burn server calls for 100% of the visitors regardless of their OS, now with DTM as the campaign targeting layer, we're only using server calls for those that match our targeting rules:

Global Mbox strategy

If you're currently using a global mbox it does pose the question whether you'll want to continue as this will undoubtedly be more expensive. The primary reason for adopting a global Mbox strategy was to have the ability to add mboxes to any page through Target opposed to bothering IT, however you can now do this through DTM and it's *significantly* more user-friendly (a marketing person can do it) compared to adding them in Adobe Target. Here's how easy it is in DTM. So I'd recommend you disable the global Mbox in the Marketing Cloud before you download:

When to use Target or DTM

There will be situations that you'll need to define targeting in Adobe Target for example at Experience or success metric level, here's how my responsibility split would look across both systems when creating an optimisation campaign:

DTM	Adding Mboxes, Campaign level targeting (including scheduling).
Target	Outputting content, Experience and success metric targeting, defining success metrics.

Both Adobe DTM and Target are highly complementarity and I'd recommend you give them a spin if you haven't already. Any questions, feel free to ask below.