For me the Leatherman is an additional item to carry along with a multitool, not a replacement. I use and love the Crank Bros M19 and the Leatherman Squirt.
Yep. I've used the leatherman juice to do some pretty neat stuff, pry off jammed cranks that some poor soul on a rental got stuck with mid-ride miles from anywhere, preload cranks on the trail without the shimano trail, they are usually infinitely better than any bicycle-tool when using the screwdriver function, etc. I take this with me on all rides.
That said, I agree completely, it's in no way a replacement for a proper bicycle multi-tool. If you can only take one, the toppeak aliens are outstanding tools. Some more minimal designs do fairly well and just include the most common stuff you'll need, some people may not go out far enough to have to worry about the more rare breakages, etc. I was recently lucky enough to get hit by a car last November and finally lose my crank brother's rust-o-matic-17 russian-submarine grade iron tool that doesn't push chain pins out far enough to re-insert a shimano pin-tool, so I got a nice lyzene that is compact and doesn't seem like it will suffer from the same issues.