Absolutely the cam and a half and other hybrids have to be timed. And the cam and half is also somewhat susceptible to "synch" problems (though not to a large degree)

Basically there are two types of hybrids. Hoyt's system (which browning also uses) which is a little closer to a two-cam bow (it uses a cam shaped track at the top for take-up), and there is the CPS (Controlled Power system) that uses a round take up track (like the idler of a single-cam) which Darton, Martin, Merlin,Champion and some others use.

They are both very similar, however due to the difference in the top "cam", the Cam and a half is susceptible to out-of synch conditions (like a two-cam bow, but not nearly to the same degree). The Cam and a half also does not generally yield perfectly straight and level nock travel through the entire draw length range of each module size (generally performing best at the short and mid length settings), however the nock travel is still better than many single-cam bows.

The CPS has better nock travel throughout the entire range of draw lengths. In fact it's pretty much dead level and straight unless you really goof them up or set up them up incorrectly (assuming it's on an appropriately built riser design that allows for perfectly level nock travel..not all CPS bows are).

I shot the CPS on several bows for several years (including a current 2004 model) and have also owned 4 bows with the Cam and a half. I think in general the CPS style draws a little nicer: it peaks sooner, rolls over smoother and lets off sooner. The Cam and a half is a little more bumpy (but certainly not objectionable) rolling over. I do like the cam and half better overall though because as Ash pointed out it's a little easier to tweak to get a more forgiving set-up (somewhat like a dual cam that can be set slightly off synch to cause the arrow to lift slightly off the rest during the power stroke). You can do this with the CPS too, but like SA spoke of, they can be more finicky when everything is not in perfect harmony. The Cam and a half seems to relish the *slightly* "out of harmony" settings. However the Cam and half can get dowright horrible accuracy-wise if the top cam is over rotated. Most of the Cam and half bows coming into the shop are set-up quite well out of the box, but on occasion I've seen some that were not set-up correctly.

So in essence they both can get out of time, and the Cam and half can also get out of synch so to speak , however neither are nearly as critical as two cam bow (or some one-cam bows) under most circumstances.

With a high quality string and cables, both are easy to set up by a competent tech, will stay that way, and offer very good or perfect static nock travel. I would be more concerned with purchasing the model that fits and feels best (and making sure you have that high quality rigging) than worrying about whether it's a CPS or a Cam and a half. They are both extremely accurate, shootable systems.