I concur, you can mix and match. While the Titlist front derailleur may appear similar to Dura-Ace front derailleur with a cursory glance, they are very different and only share a few nuts and bolts. All four are good derailleurs, but most consider the SunTour rear to be slightly better than the Shimano, by virtue of its slant parallelogram. However, on the front most would probably give the nod to the Dura-Ace by virtue of the fact that it is lighter and does not shift "backwards", as noted by Top506. However, most people adapt very quickly to the reverse front shift, provided they are not constantly switching bicycles with both normal and "backwards" shifting front derialleurs.
It is interesting that a lot of knowledgeable cyclists seek out SunTour's "backwards " shifting front derailleurs. These derailleurs use the spring tension to shift from the small to large chainrings. It is argued that it is logical to use the spring tension to make the more difficult upshift. However, most of this same group sees little or no value in Shimano's Rapid Rise rear derailleurs which use the same concept.