I usually have one or more of those kicking around. I use them for lighting the BBQ mostly (the piezoelectric starter hasn't worked for years). My biggest gripe with these is that I have found them to be largely unreliable - could be a manufacturer specific thing I guess, but I've got a generally low opinion of refillable butane lighters.
I can definitely see these being better at fire-lighting than a traditional lighter though. It would be way easier to get the flame where you need it but, as you said, the bulk would put me off including it in my backpacking gear (I'm pretty sure I have one in my kitchen stuff for car camping though). That said, I personally hate using lighters; I'll use a firesteel or match over a lighter every time I'm given the choice.
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Victory awaits him who has everything in order — luck, people call it. Defeat is certain for him who has neglected to take the necessary precautions in time; this is called bad luck. Roald Amundsen