"Titanium" needles are actually just regular needles with a Titanium Nitrite coating on them. It does a couple of things for you, it is a slicker surface, so the needle penetrates fabric easier, and because it's a coating that's harder than steel it helps maintain the point longer.
I use them when I embroider a design with a high stitch count, just so I don't have to change needles. I usually change my regular needles daily and I can't justify the expense for piecing. I will chase some down for the longarm and see if they really last long enough to justify using them full time.