Until recently I was quite happy with both focus blending and also pano blending using CS5 for landscape photography. However, a few months ago I started to find landscape images that CS5 focus stacking failed to blend well. These were images made of just 3 shots, but the very near forground, near the bottom of the frame had regions out of focus. Instead, I tried Helicon Focus, purchased it, no problems anymore.
Yesterday, for the first time I found a two shot pano, made with a the Canon TS-E 17 mm lens that CS5 failed to combine (the CS5 message said it could not create a successful pano). The shots were made on an Induro PHQ-3 pano head, the TS-E was tilted for DOF and shifted down perhaps 6 mm, but the camera itself was also pitched down (making it a more difficult case). There was considerable overlap between the two frames. I tried the various CS5 perspective choices, some of which has always woked in the past. Since CS5 failed, I decided to download the newest trial version of PTgui (9.1.3), and it worked, producing a blend I could use to produce a final image.
So, based on my experience so far, it appears that while CS5 will work much of the time, the specialized tools (Helicon Focus and PTgui) do have there place.