My Juice KF4 usage during the challenge...
Tools used regularly: Blade, Needle Nose Pliers, Philips Driver
Tools used quite a few times: Awl, Serrated Blade, Medium/Large Flat Driver
Tools used occasionaly: Regular Pliers, Small Flat Driver, Wood/Metal File
Tools used once or twice: Saw, Ruler, Wire Cutters, Diamond Coated File
Tools never used: Hard Wire Cutters, Extra Small Flat Driver
Note:- I used the bit driver kit once to get to a deep hex bolt.
Tools missing in the KF4 and thoughts...
Scissors - The KF4 would have been perferct for me if it had scissors instead of a saw. But no MT is perfect.
Cap lifter- All the Squirts has one, just saying. No biggie for me though. Can do the coin on a table trick.
Can opener - Never needed one. Would have needed it if I was traveling with my wife to open milk cans.
Tweezers - Never needed one. Would have been nice if it had one. Sometimes they are very useful.
Cork screw - Never needed one.
I guess if I had a Micra or a Squirt in my keyring the shortcomings of the KF4 would have been covered. I hate carrying too many things with me so most of the time I EDC a S2 and nothing else and the only thing I miss in that is an Awl.
Conclusion: If you need to go small, light and can have only one tool then any Juice other than the XE6 and Pro will be good choices. As a plus it's size, appearnce and eye catching colors does not look threatening when you take it out in the mall or at work. Easier to use than a key chain size MT, got decent pliers and can do most tasks a full size MT can do.
Also enjoyed seeing others do different thins with their Juices too. Good job everyone. And thanks Ob1 for hosting