I haven't had a single instance of the failure-to-launch problem with Quicksilver. But even though Quicksilver works as advertised, its interface is less clever than LaunchBar's in ways that quickly add up and make QS take more work to use than LB. For example:
-all the good plug-ins are outdated
-The menu items interface hasn’t worked in years.
-The interface can't be repositioned.
-the interface's font is too small, while its graphics are huge,
making the interface waste a lot of space and you can't read filenames and URL's as easily
-No emacs-style cursor control
-No direct file manipulation shortcuts. You do it via an action, but
no multiple selection via the normal interface.
-Calculator isn't direct, but via an action, and the interface's
font is too small.
-I can't figure out how to use the 1Password interface.
-Abbreviaitons are not free, but must be literally contained in the original.
-I can't figure out how to use my existing Firefox searches
-Generally more cumbersome (more keystrokes, more complicated
methods) than LaunchBar.
-Calendar plug-in is old, for iCal and doesn't allow creating events
at both a specified time and a specified date. Creating a ToDo
creates a Reminder in the default Reminder list.
-Quicksilver has nothjing like LaunchBar's immediate action on a file
because its preload doesn't work.
-The support group is on Google Groups.
-It's clunkier for file manipulation than LaunchBar.
QS is suffering from lack of development of its extended features, apparently because the community is too small. Over the past five years, it's lost more and more functionality. LB has the niftier interface, I guess because the promise of income gives the devs more incentive to keep polishing it. But this failure-to-launch issue is a real bear. I mean, it's LB's only glitch that I know of, but it's a doozie. Today, once again, I had an entire Word file's contents highlighted and when LB failed to activate with cmd-space, the space clobbered the entire Word file. As mentioned, disaster seems to always be easy enough to avoid via cmd-z or close-without-saving, but somehow I have the feeling I'm cruising for a bruising. QS's inferiority is significant enough that I do prefer LB.
A new discovery today: Alfred. I'd looked at it in the past, but chose LB at that time. But with LB's failure-to-launch problem, I have a lot of incentive to find something that will offer the same functionality with greater reliability. I'm just learning Alfred, but it looks like it will provide all the same functionality as LB, just arranged differently. No failures to launch yet. And the developer and user community looks more lively than LB's, partly due to the retail price. Oh yeah, you have to pay up for Alfred's Powerpack, or else you sacrifice way too much functionality. One irksome thing about Alfred is its lack of a single-key trigger, but it does do several things in different ways than LB and that are nifty in a different way so that it may be, on the whole, the more labor-saving and less frustrating interface.